Pluto on
the DSS plates

Pluto identified by TheSky and RealSky!

FITS RealSky image with Pluto Identified

Stellar labels and Pluto

Not all stars labeled for clarity!

Also omitted is the data from the USNO-B1 complete set with 1 billion stars.  See Below.

Download image and .SKY document file

The above has the RAW fits image and the document file for TheSky.

The FITS information found in the RealSky image gives us the Date and Time the image was taken.  Choose the Observatory location file in the Data | Site information dialog box.   Now choose Palomar Observatory from the list.  Since the time is given in universal time you will need to set a time zone of zero NO daylight and then the date for March 22, 1955 at 5:34 A.M (UT).

Now search for Pluto in TheSky program (Edit | Find Pluto) and generate the RealSky image.   Works with the 102 CD-ROM set of the Palomar Sky Survey (POSS/DSS) as well.  I used TheSky to compute where Pluto was during the time the images were taken (found in the FITS header) and zeroed in from there.   Pluto was reasonably simple because it moves very little over a long period of time.  Can you find Uranus on the plates?
 

How about minor planets on the plates?  Why not?  Keep in mind that outdated orbital elements can be problematic in this case!

Here is the Object information for Pluto on this date generated from TheSky6.  If you enter the proper date/time and location from the FITS header then center on Pluto and create a DSS image you will see Pluto.

Same field with over 1 billion stars plotted!
(USNO-B1 with 1 billion stars + UCAC2)

All stars to ~19th magnitude accounted for by USNO-B1 full!
RealSky/DSS copyright

Note the above 14th magnitude intruder from the USNO-B1 full dataset located just above Pluto!

For Clarity Pluto removed

And finally
RealSky/DSS copyright

An error?

Yes. The 80 gigabytes of USNO-B1 stellar data (1 billion stars) shows a 14th magnitude star very near Pluto.  Because it is 14th magnitude that makes the star nearly the same brightness as Pluto.  Even when computing for 50 years of Proper Motion the star cannot be accounted for unless it was originally Pluto!  My conclusion is the USNO-B1 star is therefore an error.  Here is the data for the star from the USNO-B1 data.  I simply cannot account for it.  Could this star have been Pluto???

Object name: USNO Star
Magnitude: 14.08
Equatorial: RA: 10h 03m 26.99s Dec: +23°09'44.31"(current)
Equatorial 2000: RA: 10h 05m 54.58s Dec: +22°56'47.47"
Horizon: Azim: 154°14'43.32" Alt: +78°48'30.02"
Visibility: Rise 22:44, Set 13:02
Transit time: 05:55
Source catalog: USNOB
Hour angle: -00h 23m 33.15s
Air mass: 1.02
Magnitude B: 14.89
Magnitude R: 13.60
Screen x,y: 571.00, 326.00
Proper Motion: 91.00, 205.00
Sidereal time: 09:42
Click distance: 2.0000
Celestial type: 0
Julian date: 2435188.7319
Angular separation: 00°00'19.53"

NOTE:  The missing USNO-B1 star is not in the photograph.  There is only one 14th magnitude object here and it matches  exactly the position for Pluto on the date and time of the FITS image as computed by TheSky for the Palomar Observatory.

RAW FIT image

Bright object in center
RealSky/DSS copyright
My conclusion, it must be Pluto

Pluto from TheSky6

Object name: Pluto
Magnitude: 14.4
Apparent magnitude: 14.4
Equatorial: RA: 10h 03m 26s Dec: +23°09'26"(current)
Equatorial 2000: RA: 10h 05m 54s Dec: +22°56'29"
Horizon: Azim: 152°01'53" Alt: +78°21'48"
Apparent angular diameter: 00°00'00"
Visibility: Rise 22:47, Set 13:04
Transit time: 05:58 Transit: 5:57 AM on 3/22/1955
Set: 1:04 PM on 3/22/1955
Rise: 10:46 PM on 3/22/1955
Phase (%): 99.99
Object type: Pluto
Sun distance (au): 35.01
Hour angle: -00h 23m 35s
Air mass: 1.02
RA rate (arcsecs/sec): -0.0008
Dec rate (arcsecs/sec): 0.0002
Heliocentric: l: 146°21'52"b: 10°17'05"r: 35.0086
Geocentric: l: 145°23'02"b: 10°31'38"r: 34.2115
Geocentric mean: l: 145°22'58"b: 10°31'37"r: 34.2116
True RA: 10h 05m 56s
True Dec: 22°56'20"
Altitude w/refraction: 78.3665
Heliocentric longitude: 146°21'52"
Heliocentric latitude: 10°17'05"
Sidereal time: 09:42
Click distance: 2.0000
Celestial type: 34
Index: 9
Julian date: 2435188.7319
Angular separation: 00°00'03"

From the FITS header created by using the 102 CD-ROM set with CCDSoft

DATE: 26/09/05
DATE-OBS: 22/03/55
UT: 05:34:00.00
SITELAT: +33:21:24.00
SITELONG: -116:51:48.00
PLTLABEL: E1352
REGION: XE371
PLATEID: 072A
OBJCTRA: 10 05 52.494
OBJCTDEC: +22 56 16.13