Automated Astrometry - TheSky6/CCDSoft

Background

TheSky and CCDSoft have very powerful tools which allow you to perform plate constant astrometry accurately and easily. Assuming you know the scale of the image in arc seconds/pixel AND assuming the CCD image was taken using TheSky and CCDSoft the astrometry is literally one mouse click or even completely automatically via external scripting).

See the following document with complete details <--- Click here for more  including trouble shooting.

TheSky version 5 users are encouraged to upgrade to TheSky6. Although the astrometry can still be performed using TheSky 5 with CCDSoft the astrometric solutions will be compromised since TheSky 5 does not have access to the newer more accurate stellar data, the USNO-B1 and UCAC2. You can expect up to 5 times more accurate astrometry using TheSky6 and CCDSoft instead of TheSky version 5. More often than not RMS solutions under 0.25 arcseconds are easily obtainable.

What level of accuracy is "good enough"?

Because the astrometry routines use Image Link technology it is best to become familiar with it's use. There are also several other advantages to using Image Link even while taking the CCD images, initializing the telescope, or mapping the scope with TPoint.

If you cannot get your images linked routinely you will not be able to perform the Astrometry. CCDSoft relies on TheSky to automatically find all corresponding stars on the image that match the active stellar catalogs present in TheSky. These include the Hipparcos, Tycho, GSC, USNO-B1 subset, UCAC2, and the USNO single CD-ROM of 54 million stars or the 11 CD-ROM set containing 526 million stars.

Important Note: Performing astrometry requires 12 to 16-bit RAW data. If the sample image provided here is saved in an 8-bit format (.jpg, .gif, etc. not FIT) Insert WCS (World Coordinate System) Auto Astrometry will fail!

Because accurate astrometry requires accurate time stamping of the images as do most goto telescopes you need to make sure the date and time settings for the PC clock are as accurate as possible when imaging. The following page has details on how to accurately set your PC clock.

Astrometric routines

Is the astrometry performed by TheSky and CCDSoft really accurate enough?
 

Yes, most definitely! (qualifier - when accurate stellar datasets are employed)

When using TheSky version 6 Professional and CCDSoft version 5 you can often achieve astrometric solutions that are good to less than 1/4 of an arcsecond and achieving 100th of an arc second RMS using a dozen or more stars is not unheard of. That is because TheSky6 uses the UCAC2 data and is also supplemented with the USNO-B stellar data. Currently these are the most accurate stellar catalogs. See example astrometric solution demonstrating this below.

Keep in mind that RMS solutions under 1/2 an arcsecond are actually MORE than accurate enough to submit to the Minor Planet Center. Anything at or below 0.25 one quarter of arcseconds is actually quite good and again more than accurate enough. This should easily be obtainable using TheSky6/CCDSoft.

What qaulity of measurements should I am to produce? <----- Taken directly from the IAU's guide

Astrometry is a field where bad measures are generally of little or no use. It is important that observers can consistently produce observations with a consistency of <1" for observations using the same comparison stars, and a night-to-night consistency limited only by the comparison star catalogue.

The astrometric routines used by TheSky and CCDSoft are the PC-ASTROM routines as described in the CCDSoft documentation. See the copyright notice below. These routines are the "standards" for the United Kingdom (UK) they work extremely well, have been around for years, were written by "professionals" that is they are extremely accurate routines So why rewrite the wheel as I always say.

The author of TPoint Mr. Patrick Wallace encouraged Software Bisque to employ these astrometric routines. Frankly we couldn't be happier with the results.

PC-ASTROM Copyright Notice
“PC-ASTROM – A Plate Reduction Program”

Copyright P.T.Wallace and Starlink Project, CCLRC, UK, 1999. All Rights Reserved. Reproduction, adaptation, or translation without prior written permission is prohibited, except as allowed under the copyright laws.

Tpoint Software
19 Sutton Wick Lane, Drayton, Abingdon, Oxfordshire
United Kingdom OX14 4HH
TPoint Software Web Site: http://www.tpsoft.demon.co.uk (internet link)

In addition to the PC-ASTROM routines TheSky and CCDSoft use the very well known and widely used and well documented "Source Extraction" routines for identifying the stars in the CCD image.

CCDSoft Preferences

Use CCDSoft's File | Preferences to access the following dialog and set which version of TheSky to use. Again, version 5 users should consider upgrading to version 6.

Choose which version of TheSky
 to use with CCDSoft

Check either version 5 or version 6
under Astronomy software integration

CCDSoft will automatically launch TheSky6 or TheSky version 5 (depending on the above selection) when needed if it is not already up and running.

See the following document with complete details on performing astrometry with Image Link,  including trouble shooting <--- Click here for more.

TheSky Remote connections

If you get an error when CCDSoft attempts to launch TheSky either the version is NOT installed on the system or you have simply selected the wrong version here. Both versions of TheSky must also explicitly "Allow for Remote Connections". See below.
 

Use TheSky's Telescope | Server Settings and enable "Allow remote connections" here.

Enable remote connections

Check those that apply

If CCDSoft while attempting to launch TheSky fails or trying to perform the Research | Insert W)orld C)oordinate S)ystem/Auto Astrometry feature fails either TheSky is not allowing for remote connections, see above, TheSky is simply not installed on the system, or you have not chosen the correct version of TheSky in the CCDSoft Preferences, again see above.

ERROR message!

TheSky cannot be launched!

See the following document with complete details  including trouble shooting <--- Click here for more.

Sample raw CCD Image

By using the sample CCD image below you can get started immediately because the image just works. I recommend you try my albeit older CCD image from way back first before attempting astrometry on your own. Walk then run!

Sample FITS Image

(Click on the image to download the file named MPL51.FIT)

Click here to see the 20 inch automated scope

DOWNLOAD all three (285K) files zipped (the FITs file, the corresponding .SKY document file, and the Source Extraction .SRC).

FITS image details
 

15 second exposure to ~18th magnitude,
20-inch f/4 and Apogee AP-7 CCD Camera
June 26, 1997 at 3:46:25 a.m. local time

June 26, 1997 at 9:46:25 a.m. Universal Time (UT) no daylight and time zone zero
Golden, Colorado

The date and time of the CCD image are stamped in Universal Time (UT) not local time for Golden Colorado. Since there is a minor planet on the image you will need to change your Data | Location in TheSky program accordingly! Or just CCDSoft's option Research | Comparison Star Chart to do this for you!

TheSky's Location to match the image information

No daylight and Time Zone Zero for Universal Time (UT)

(click on the image to get the .SKY document file)

Simply choose the site Blue Mountain Observatory, Colorado from TheSky's list of observatories under the Predefined List of locations, now renamed to SBO Software Bisque Observatory. Change the date and time in TheSky to June 26, 1997 at 9:46:25 a.m. UT (time zone = 0 and Daylight Not Observed). If you do not enter the date and time correctly the minor planet position will not be plotted on the image for you.

Also make sure the Data | Time settings matches too. See below.

Data | Time Settings

June 26th, 1997 9:46:25 AM Universal Time (UT)
(click on the image to get the .SKY document file)

Better Yet - Insert Minor Planets

You can also use CCDSoft's feature Research | Insert Minor Planets to identify all minor planets within the field for you. TheSky is then used to compute the positions of the "Extended minor planets" (~300,000 at the time of this writing) and a circle is placed on the image showing where any found minor planets are located by TheSky. See below!

Warning! To use the feature make sure you have an extended minor planet data file present. Something like MPCORB.DAT or ASTORB.DAT. <--- Click here for details!

If you do not have an Extended Minor Planet file present the option will fail. You will either get an error message indicating there is no extended minor planet file or simply No Minor Planets inserted!

Research | Insert Minor Planets

Minor Planet has been inserted!

The green circle indicates the location of the minor planet as computed and found by TheSky. And now even Better yet. Have TheSky create the corresponding chart for you! See below.

Comparison Star Chart

When TheSky and CCDSoft have taken the image for you the information needed to set TheSky to match the image have been added to the FITS header. Use the option Research | Comparison | Star Chart. The latitude/longitude, date and time are then passed into TheSky. And if you have computed all known minor planets using the Extended Minor Planets any and all known minor planets will be identified for you. The RED vector line is the 24 hour path showing the direction and distance the minor planet will travel. The large red minor planet symbol indicates the current position for the date/time and latitude longitude set in TheSky.

WARNING!

When using the feature to set the date/time in TheSky from CCDSoft using Research | Comparison Star Chart you will need to make sure that the Daylight Savings option is set to Not Observed. This setting is not passed in from CCDSoft! The date/time and location are using Time Zone = Zero but you must also use daylight not observed.

Time Zone must be set to ZERO

and Daylight set to Not Observed

Research | Comparison Star Chart

Same field created by TheSky
CCDSoft sets the location and date/time from image
requires the fits image was taken with TheSky/CCDSoft

And finally the actual CCD image as Image Linked directly in TheSky with the minor planets labeled.

Star Chart created by TheSky

Same field, date/time and latitude and longitude

After changing TheSky's site information you will now need to compute or re-compute the positions for the Extended Minor Planets in order to see where the Minor Planet (51) Nemausa is located in the CCD image. Use the menu option Data-Extended Minor Planets option to load an extended minor planet file. Any of the minor planet files we provide will work fine. Here is a good source for the latest minor planet orbital elements.
 

Download the following document file for TheSky and place it in the ..\TheSky\Documents folder. 

MPL51.SKY

DOWNLOAD all three (285K) files zipped (the FITs file, the corresponding .SKY document file, and the Source Extraction .SRC).

See the following document with complete details  including trouble shooting <--- Click here for more.

Launch TheSky and click File | Open to load the  MPL51.SKY document and all of the Site information will be set correctly for the above image.

Because TheSky6 boasts the newer and more accurate stellar catalogs the USNO-B1 (subset) and the UCAC-2 the astrometric solutions are often times significantly improved. The following dialog shows the astrometry performed on the above image using TheSky6 and CCDSoft.

The Residual Filter

The Residual Filter (located under the SETUP button) was set to a value of 0.1 to INCREASE the accuracy of the solution. Note the RMS solution is good to 0.06 arc seconds! Keep in mind the Minor Planet Center only requests solutions on the order of 0.25 to 0.5 arc seconds using 6 to 12 stars or more! So this astrometry is now 5 times better than the recommended because of the better stellar data.

If you want to change the residual filter press the Setup button. The lower the number here the better the astrometry! Find what works. If you have too few stars used in the solution (less than a dozen) it is best to use more stars by entering a larger number.
 

Residual Filter

Setup

Research | Insert WCS (Auto-Astrometry)

Now perform the Astrometry

When the correct scale of the image has been entered in arc seconds/pixel press continue. If TheSky needs to be launched this can take a few moments. And, it does take a bit of time to perform the astrometric solution.

The following RMS solution is found by setting a residual filter to 0.1 using the SETUP button. This will automatically throw away all stars with poor input coordinates. And because there are so many UCAC2 and USNO-B1 stars available it still finds more than enough stars to provide good solutions. 6 to 12 stars in most cases is all that is need to perform astrometry accurate enough to submit to the Minor Planet Center.

0.06 arcseconds RMS!

Using 20 stars total from the UCAC2 data

Remember, if you can not perform an Image Link on the image you can not perform Auto-Astrometry.

See the following document with complete details  including trouble shooting <--- Click here for more.

Don't know the center of the image

You can still do the astrometry on an image by knowing the approximate RA and DEC of the center of the CCD image. Then just use Image Link! Since my image was taken automatically with Orchestrate, while I slept, the CCD image has the coordinates of the telescope's position automatically stamped in the FITS header. Or you know the date and time along with location so you can also center on the minor planet too, Edit | Find MPL 51 Nemausa in TheSky using the Extended Minor planet file.

Image Link can search as much as twice your field of view for a match. Just get close to the center of the image.

Go directly to the coordinates

Center TheSky display on coordinates
RA: 19h 08m 33.0s Dec: -06°02'04"

Or, find the Minor Planet 51 Nemausa and Center it. Important:  Make sure the Date/Time and locations are set correctly first if you choose to center on the minor planet position instead of the RA and DEC center of the image! See the above SKY DOCUMENT MPL51.SKY.

Next zoom out to 30 arc-minutes to give Image Link room to find the match. The easiest way to do this is by entering "Z30M.". That is Zoom to 30 arc minutes and "." center. This takes you directly to 30 arc minutes.

Find Dialog Box

Zoom out to 30 arcminutes

Now use the Link Wizard on the Image Link Tool Bar to search for a match. Note the next release of CCDSoft will not require this additional step. The advantage of using the Image Link tool is that it will report the scale of the image, center of the image, and the north angle of your camera.

See the following document with complete details  <--- Click here for more including determining SCALE.

Image Link Tool Bar

Link Wizard button

Successful Image Link from sample image provided. Note the Image Scale is correct at 2.385 arc seconds/pixel.

Found a match!

Click Accept Results

Trick:  You can just Edit | Copy the Image Link data from the dialog.

Copy the coordinates from Image Link

Use the "Less Information button"

Use the button found on the lower right of the Object Information "Less Information" to minimize the size of the box. See above "Less Information" icon. See minimized dialog below allowing you to grab the text.

Grab the Epoch 2000 Coordinates
out of the Object ID Box

Use the Image Link information

First you need to get to the "Image Link" information by moving down the list of objects identified. "Image Link" will not be the first entry in the list. USE THE DOWN ARROW to get to the last entry in the list to see the Image Link information.

Next highlight the line showing the current coordinates. This is done using the mouse drag over the text. Then Right Mouse click and COPY to copy these coordinates to the Windows Clipboard. Go to CCDSoft and press SHIFT+INSERT to insert the coordinates into the Preliminary Astrometric Data dialog box. See below.

Coordinates copied from Image Link

Data inserted from Image Link
Edit Copy | Edit Paste

You must STRIP OFF the RA: and Dec: headers and convert the data into the correct format. If the data is not entered correctly you will not get the Image Link to work and the Auto-Astrometry will fail. The correct format for the data is shown below.

00h 00m 00.0s +/-00d 00m 00.00s or in our example,
19h 08m 41.09s -06d 01m 49.62s

Source Extraction (Sextractor)

For those that wish to see exactly how the Source Extraction routines work for identifying stars, computing their positions, determining flux values, FWHM, etc. the web offers several papers on subject. This is also true of the Source Extraction Setup Parameters shown below.

When you have performed the astrometry on an image or used the option Research | Show Inventory on image a ".SRC" source file is created. Following is the header found in the example image.

#HEIGHT=   500
#WIDTH =   480
#TIME  =  3.773611
#       #
#   1 X_IMAGE         Object position along x                         [pixel]
#   2 Y_IMAGE         Object position along y                         [pixel]
#   3 MAG_APER        Fixed aperture magnitude vector                 [mag]
#   4 FWHM_IMAGE      FWHM assuming a gaussian core                   [pixel]
#   5 FLAGS           Extraction flags
#   6 CLASS_STAR      S/G classifier output
#   7 ELONGATION      A_IMAGE/B_IMAGE
#   8 ELLIPTICITY     1 - B_IMAGE/A_IMAGE
#   9 A_IMAGE         Profile RMS along major axis                    [pixel]
#  10 B_IMAGE         Profile RMS along minor axis                    [pixel]
#  11 THETA_IMAGE     Position angle (CCW/x)                          [deg]

The data from the image then follows,

There are several default parameters that are used by Source Extraction. Rarely do the default parameters have to be changed. If you are unsure about a setting it is best to leave it alone. To access the Sextractor Setup dialog use Research | Analyze Folder of Images | Pre Analyze | Setup. See below.

Source Extraction Setup

Change only if needed!

NOTE:  Use the option Research | Show Inventory to see the effect the change has! You can also inspect the .SRC files being created to see what if anything has changed.

How can I check the accuracy of the astrometry?!

Easy enough!

Here is a creative way to easily see if the astrometry is valid. Simple. Take the astrometric positions computed and plot them directly on top of the CCD image. The astrometry is correct or it isn't. If done correctly the astrometric position will match exactly where the object is in the CCD image. If it doesn't go back and try again!

This trick can save embarrassment!

By having TheSky plot the astrometric position(s) you have created over the CCD image you can rest assured everything was done correctly. The text file with the astrometric positions can be compiled into an SDB file (TheSky Database File) and plotted directly on top of the CCD image or you can manually add each astrometric position into the Data | Add User-Defined Data section for a quick reality check.

You can use the header text I have created below to plot the astrometric positions in TheSky FROM any source! Because the formatting for the MPC is standard you can plot the astrometric positions created by TheSky and CCDSoft or any other program that is capable of creating the file formatted for the MPC directly. Just attach this header to the text file and compile the data in TheSky. Very straight forward. All the work is done for you.

You can even leave the initial lines of text with the observer information in file if you choose to. It won't be a problem as long as you comment the data out with semicolons.

;COD XXX
;CON S. Holmes, 221B Baker Street, London NW1 4JW, England
;CON [sholmes@mycroft.holmes.gov.uk]
;OBS H. Poirot, P. Mason, L. Columbo, C. Chan
;MEA J. Watson
;TEL 0.50-m f/3.0 reflector + CCD
;NET GSC
;ACK Batch 001
;AC2 dwatson@mycroft.holmes.gov.uk
;the above are commented out!
;Ignore lines with semi colons!
;
 

>SEARCH 1,14
>RAHOURS 33,34
>RAMINUTES 36,37
>RASECONDS 39,43
>DECSIGN 45,45
>DECDEGREES 46,47
>DECMINUTES 49,50
>DECSECONDS 52,57
>MAGNITUDE 65,69
>OBJECT TYPE 55
>IDENTIFIER MPC Astrometry
>PARSE "Designation" 1,14
>PARSE "Year Month Day" 16,31
>PARSE "Observatory Code" 78,80
>LOADMEMORY

  BSQ063   C1997 06 26.40732 19 08 29.08 -06 02 32.2          11.0        XXX

Locate the MPC text file with header

Now just Compile the text file

Just click the entry name listed and center on the object's position.

Edit | Find objects
under Sky Databases (SDBs)

Nice!

Reference Point and

Minor Planet Symbol

Again, a GREAT reality check!

WCS (World Coordinate System)

The World Coordinate System is used by TheSky and CCDSoft when performing astrometry. If there is such a thing as a "standard" regarding how astrometry should be done this would be it.

Note that the stars used in the astrometric solution are then stamped in the FITS header for convenience. Use View | File Information and select the "Edit Header" tab.

NOTE:  The UCAC2 and USNO-B1 stars do not have unique identifying numbers like the GSC, Hipparcos/Tycho, and other stellar catalogs. There for they are only referred to as UCAC2 or USNO-B1. This also means you cannot simply search for them either. The keyword used for the stars is OBJCT followed by a number. See below.

Stars used in the astrometric solution

Added to the FITS header

Show Inventory

If you wish to see what stars in the image are being used in the astrometric solution they can be identified for you. Use Research | Show Astrometric Stars and small yellow markers are placed on the image showing which stars were used.

Show Inventory displays stars used in the solution

And/or stars as found by Sextractor

The above image also shows what objects are identified by the Source Extraction routines along with their respective sizes. These are represented as purple circles on the image.

Summary

Download the above sample FITS image provided
Download the MPL51.SKY document file and load in TheSky6 (File | Open MPL51.SKY)
Load the FITS  image into CCDSoft (File | Open MPL51.FIT)
Use Research | Insert WCS/Auto-Astrometry
Enter the scale of 2.39 arc seconds/pixel and press continue
Use Research | Insert Minor Planets to identify the location of the minor planet
 

That all there is to it. Astrometry performed with one mouse click (and 30 man years of software development behind it ;).

Submitting a minor planet position to the MPC

For information regarding submission of minor planet positions to the Minor Planet Center please see the following,

http://cfa-www.harvard.edu/iau/info/ObsDetails.html

Now that the astrometry has been performed on an image you may wish to submit the astrometric position of the minor planet to the MPC. Easy enough. Enable the astrometry tool bar - View | Tool Bars | Setup | Astrometry. The last icon on the Astrometry tool bar allows the computed centroid of any objects position to be added to a text file compliant to the MPC's format.

Astrometry Tool Bar

Use the MPC
Observation icon

The centroid tool computes a sub pixel position of the object you mouse click on. That position can then be added to a text file that follows the IAU format. Pick the centroid tool and carefully mouse click on the minor planet. I find zooming in makes this quite easy.

The Zoom Tool is found on the Standard Tools bar. See below.

Zoom in

and out

The following shows the image centered on the Minor Planet as identified by TheSky zoomed in to enlarge the minor planet. This makes mouse clicking on it quite simple.

Use MPC Observation Tool and mouse click on the minor planet.

Get in close and personal!

But Wait!

The white centroid marker is not exactly centered on the minor planet. What gives?

Computing a weighted sub pixel average of the object is actually more accurate than just clicking on the center of what appears to be the center. You can trust the software is computing the proper center position of the objects for you! That is on STELLAR objects and minor planets. Point source. Trying to use this on a comet is something else!

If you feel you must override the automatic centroid (i.e. Super Nova embedded in a galaxy) you can actually CONTROL+MOUSE click and get the coordinates for any pixel! NOT NORMALLY RECOMMENDED.

In our example do not adjust the time

Only applies if you used LOCAL time!

The time zone adjustment was added to CCDSoft for those that did not use the option in CCDSoft (or other imaging software) to take the images using Universal Time instead of local time. The IAU requires the images be stamped in Universal Time (UT) not local time. Adjust if necessary!

Next the New Observation is of type Minor Planet. You can enter your own designation here. Click the button to "Add Observation To List". Your astrometric position is now added to a text file for submission to the MPC.

Use of Mid-Exposure Time

NOTE: CCDSoft will add the MID-EXPOSURE time to the Minor Planet Observation as required by the Minor Planet Center. The original time in the FITS image remains untouched. The newly computed value for Mid-Exposure uses the start time and exposure length to determine MID-EXPOSURE. However, this time is not stamped within the FITS header, nor does that follow the FITS standard. Writing an EVENT to stamp the additional MID-EXPOSURE key could easily be written but this just isn't necessary.

Minor Planet Center Observation dialog

Add Observation To List - note mid-exposure

Here is the ASTROMETRIC RA and DEC position for the known minor planet "MPL 51 Nemausa" as computed by TheSky and CCDSoft.

Designation   Date         Time           RA              Dec        Estimated
                  Year                       h   m    s        d   m  s    Magnitude
   BSQ058 C1997 06 26.40732 19 08 29.08 -06 02 32.2 11.0 XXX

How do we know this position is accurate?
 

Simple: First with a known minor planet like 51 Nemausa which has a reasonably well established orbit just compare the astrometric position above to the computed (predicted) position made by TheSky for the EXACT same date and time AND location (Earth location parallax comes into play here) from the image.

Of course under normal conditions this is unnecessary. Most of the time you will be performing the astrometry on minor planets where the orbit has not been accurately established. Or where the orbit can be refined for a given point in time for accurate minor planet occultation's' where up to the last minute astrometry is welcome. By supplying good consistent accurate astrometry the professionals can use this astrometric data to help refine the orbits of many objects. Well worth contributing.

DO NOT use a geocentric (center of the Earth) location or the effects of parallax will cause a slight error albeit quite small but relevant when you are at the one hundredth of an arcsecond level! Use Golden Colorado or better yet the coordinates for the observatory!

Image details

Latitude: 39°51'00.0" N
Longitude: 105°17'00.0" W
Elevation: 1990.0
Time Zone: 7.0
Daylight Saving Time: North America

IMPORTANT: Keep in mind we are working in Universal Time (required by the MPC) for the minor planet position, not local time. Time Zone Zero (0) and NO Daylight option applied make a 6 hour difference when comparing local time to universal time (UT)!

WAIT!

The positions are not exactly the same?  How can that be?  Well, this is completely expected. Note the difference is off by a 10th of an arc second in Declination and one hundredth of an arc second in Right Ascension. Hmm. As stated before when performing good accurate sub arcsecond astrometry like this the positions are accurate enough to help refine the orbital elements! Don't be surprised if the newly computed astrometric position is slightly better.

The computed position for the minor planet is TheSky's ability to compute the accurate position by numerical integration using the orbital elements supplied. These are generally good to a lesser degree of accuracy compared to performing the plate constant astrometry on the image. And now certainly the case with the newer very accurate stellar data used by TheSky.

Am I saying that the astrometric position should be considered the better of the two?  YES! Because the RMS solution is reported to 100th of an arcsecond using the astrometric procedure.

NOT Convinced??

Adding the Astrometric Position to TheSky

Consider the following.

By adding an object of type "Reference Point" using Data | Add User-Defined Data placed at the exact RA and DEC reported by the astrometric position you have the answer.

Add the RA and DEC coordinates

Reference Point or X marks the spot

When the CCD image has then been linked and aligned in TheSky display you can clearly see whether or not the astrometric position makes sense. The zoomed in image below demonstrates the high degree of accuracy of the solution which is what one expects when the RMS is reported as 0.06 arcseconds RMS! The astrometric position is plotted on the minor planet itself found on the image. Cool!

Yep looks good to me!

Wow, hard to believe!
 

NOTE:  You can email the text file with the position to mpc@cfa.harvard

DO NOT attempt repeat DO NOT attempt to submit astrometric positions until you are 99% certain the astrometry has been performed correctly!! I cannot stress this point enough. Submitting poor astrometry is embarrassing at best and unfortunately it has in the past made the professionals regard some of us as merely "amateurs" who don't know what we are doing. However, the astrometric solutions are, when performed correctly, right up there with the big boys as one can clearly see.

What time does CCDSoft stamp in the FITS header?

The start time of the exposure and the length of the exposure are stamped by CCDSoft in the FITS header (keywords TIME-OBS, EXPTIME, and EXPOSURE, respectively), as per the SBIG FITS specifications. From these the mid-exposure time can be computed as well as the end time of exposure if it were needed. The mid-exposure is used for submitting the minor planet astrometric positions to the Minor Planet Center as required. CCDSoft DOES NOT alter the original FITS entries.

In addition CCDSoft also adheres to the FITS standard keyword "DATE-OBS" which is stamped with the date and time (in UT). Example, 2003-07-17T00:35:09.834

Note the inclusion of the redundant "EXPTIME" was added specifically for a custom application (military related) and not necessarily part of the FITS "standard". As I always say "Standards are great, everyone should have their own ;).

Adjusting the time stamped in the FITs header

Let's say after a whole night of imaging you find the CCD images have been stamped in LOCAL time not Universal Time (UT). Meaning there is an offset in time based on your time zone and effect of daylight. The daylight option if used in your area will add or subtract another hour and that must be taken into consideration.

Load an image from the folder that contains the images with Time error. Use CCDSoft's Research | Analyze Folder of Images | Pre-Analyze.

WARNING!!!

There is a known quirk here! The first time you use Research | Analyze Folder of Images | Pre-Analyze you will see the following dialog.

Not what you want!

Press Ok and then try again!

On the following dialog use the FITS Modifier tab. There you will see the option Offset time (hours). Enter the proper offset in hours first then pick the folder(s) to apply the change to by Browsing your computer. When you have selected a folder that contains images if the image was taken with TheSky and CCDSoft the name of the object slewed to is shown. In this case the minor planet named 51 NEMAUSA is shown. There is only one image in this folder.

Adjusting a folder of images for time zone and daylight offset

The FITS modifier Data Analysis

Just enter the proper time zone offset here factoring in the 1 hour effect of daylight if needed! Press Start and all the images in the folder will then be adjusted accordingly. Beats having to write your own script to do this. You will be prompted with the following warning.

Answer Yes or

backup the folder first and try again

After making the adjustment to the time go back and check the FITS header View | File Information and double check the date and time to see if it makes sense.

The High Precision format - Careful..

DO NOT use the "High Precision format" option found on the Minor Planet Optical Astrometric Observation dialog! If you enable the option you will see the following message,

Warning!

DO NOT use the option if the above criteria have not been met!

Again, user responsibility here and you may save yourself some embarrassment ;).

WARNING! The sample text as per the instructions MUST be edited first! Follow the exact format and change to your name/address and equipment FIRST before submission.

DELETE all lines below here (including this line)
The name of the file that includes your observatory details is
"MPC Observatory Details.txt".
Edit this file to include information about your observatory.
Please see http://cfa-www.harvard.edu/iau/info/ObsDetails.html for a
complete specification of the format of this file.
 

DELETE all lines above here (including this line)
COD XXX
CON S. Holmes, 221B Baker Street, London NW1 4JW, England
CON [sholmes@mycroft.holmes.gov.uk]
OBS H. Poirot, P. Mason, L. Columbo, C. Chan
MEA J. Watson
TEL 0.50-m f/3.0 reflector + CCD
NET GSC
ACK Batch 001
AC2 dwatson@mycroft.holmes.gov.uk
     BSQ057 C1997 06 26.40732 19 08 29.08 -06 02 32.2 11.0 XXX
 

All of the above lines are described in detail in the on-line CCDSoft help file below.

On Line CCDSoft Help File

Please visit the Software Bisque Support forum for more details or if you need additional questions answered.

How do I obtain an observatory Code?

By contacting the MPC and requesting a minor planet to work with you can prove yourself by performing accurate astrometry on the object(s) and submitting them in the correct format. These routines make it extremely simple to accomplish this! However, there always is user responsibility here.

Please refer to the following for details on how to obtain an observatory code

http://cfa-www.harvard.edu/iau/info/ObsDetails.html