Mystery comets

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  • #574479
    Nick James
    Participant

    As a bit of a brain-teaser here are few comet-related mystery images to clear out the cobwebs after an excess of Christmas cheer. In the process of scanning comet prints for our section archive Martin Mobberley came across a number of prints which were not sufficiently well marked for us to make a good guess at the object, observer or date. These prints are set out here:

    https://britastro.org/node/20231

    Digital planetarium programs should allow us to make an unambiguous ID for the object and date. Observers may be a bit more difficult to identify but some digging in the archives may help to determine where people were on particular dates.

    There are no prizes for getting the correct answers apart from the undying admiration of your Comet Section Director. Please post any potential IDs to this thread.

    May I take the opportunity to wish you all a happy Christmas and let us hope for clear skies and a bright comet in 2020.

    #581794
    Lars Lindhard
    Participant

    A little Christmas Quiz?  🙂

    I do not know the dates or names of the comets, but If it can be of any help I can give the RA and DEC positions of the pictures.

    #581795
    Paul Leyland
    Participant

    I’m no good at identifying comets but I do know how to drive a plate solver. A local install of astrometry.net with the Gaia-DR2 database turns up the following for “Plate 1”.

    RA,Dec = (111.067,63.945), pixel scale 20.1561 arcsec/pix.

    Field center: (RA,Dec) = (111.072006, 63.929675) deg.

    Field center: (RA H:M:S, Dec D:M:S) = (07:24:17.281, +63:55:46.828).

    Field size: 3.21749 x 4.45504 degrees

    Field rotation angle: up is 114.772 degrees E of N

    Field parity: neg

    Eyeball astrometry of the image gives a J2000 position for comet’s nucleus as 07:04:43.7, +63:26:31.  Please feel free to precess that to B1950 if it helps identify the comet.

    Looks like it might be clear again tonight.  If so, solving the remaining prints will give me something to do while waiting for the photons to come in.

    #581796
    Lars Lindhard
    Participant

    Here are some of the positions

    Print 1

     Center of picture is   RA 07h 24m 23s     Dec  +63˚ 55’ 43”   East is up.

     Print 2

     Center of picture is  RA  02h 12m 24s  Dec  +66˚ 18’ 07”  North is up

      Print 5

     Center of picture is  RA  02h 14m 06s  Dec  +67˚ 33’ 51”  North is up.

      Print 6

     Center of picture is  RA 22h 49m 25s  Dec  +41˚ 53’ 58”  East is up.

     Bright star just to te right of comet is 2 And.  

     Print 7

     Center of picture is  RA 22h 35m 16s  Dec +39˚ 41’ 38”  East is up. The image is inverted.

    Same field as print 6

    Print 8

     Center of picture is  RA  08h 19m 23s  Dec +61˚ 42’ 24s  WSW is up.  Field is 45’ x 58’

     Bright star above comet is HD 68988

      Print 9

     Center of image is  RA 20h 26m 30s  Dec  +59˚ 30’ 47”  East is up.

      Print 11

     Center of image is  RA 20h 46m 31s  Dec  +57˚  27’ 25”  East is up.  Same field as print 9

     

     

     

    #581797
    Grant Privett
    Participant

    I was wondering how you did that. In the earlier pictures the stars were starlike but images 9-11 contained significantly trailed stars. Is astrometry.net really that forgiving/tolerant or did you extract some positions manually as a text list?

    #581799
    Lars Lindhard
    Participant

    Astrometry.net has no problems with star trails, so it was an easy task.

    #581800
    Nick James
    Participant

    Lars/Paul, That’s a great start with the plate solving. Now we just need to know which comets passed through those points to get the observation date and time. More difficult will be identifying the observers!

    I too am surprised that astrometry.net is so good with trailed stars/

    #581801
    Paul Leyland
    Participant

    Lars didn´t post the precise positions of the comet nucleus.  I could do so but don´t know if he intends doing so and I don´t really want to duplicate his efforts. If you have even a rough guess at the epoch for each plate the precise position should nail down the date and time of mid-exposure to a few minutes.

    #581802
    Peter Carson
    Participant

    After a happy hour or two with Astrometry.net and JPL Horizons I’ve come up with these solutions:

    Print 2
    Comet C/1969Y1 Bennett
    1970 May 23rd at around 00.00hrs + or – 1hr UT
    Up is 7.61 degrees E of N
    FOV 12.8 x 9.21 degs

    Print 3
    Comet C/1969Y1 Bennett
    1970 May 6th at approx 04.40UT
    Up is 358 degrees E of N
    FOV 13 x 9.18 deg

    Print 4
    Comet C/1969Y1 Bennett
    1970 May 4th at approx 01.15UT
    Up is 358 degrees E of N
    FOV 13 x 9.18 deg

    Would someone like to check out my conclusions?
    Can’t help with observers though!

    Peter

    #581803
    Paul Leyland
    Participant

    This the JPL ephemeris of Comet C/1956 R1 (Arend-Roland) for the night of 1957-05-19/20

     1957-May-19 21:00 A   07 03 54.81 +63 27 41.3
     1957-May-19 21:10 A   07 03 57.35 +63 27 39.2
     1957-May-19 21:20 A   07 03 59.89 +63 27 37.1
     1957-May-19 21:30     07 04 02.43 +63 27 35.0
     1957-May-19 21:40     07 04 04.97 +63 27 32.9
     1957-May-19 21:50     07 04 07.50 +63 27 30.8
     1957-May-19 22:00     07 04 10.05 +63 27 28.7
     1957-May-19 22:10     07 04 12.59 +63 27 26.5
     1957-May-19 22:20     07 04 15.13 +63 27 24.4
     1957-May-19 22:30     07 04 17.67 +63 27 22.3
     1957-May-19 22:40     07 04 20.21 +63 27 20.1
     1957-May-19 22:50     07 04 22.76 +63 27 18.0
     1957-May-19 23:00     07 04 25.30 +63 27 15.9

    The crude position I gave earlier suggests that mid-exposure was close to 21:35 UT.

    Lars: do you have precise postions for the other plates? If so, please post them and I’ll happily do the detective work.  If not. it will take me a little time.

    #581804
    Paul Leyland
    Participant

    Print 8 is also Arend-Roland.  Time of exposure is already given on the rear of the print.

    #581805
    Paul Leyland
    Participant

    Each of plates 6 & 7 are of Bennett, taken mid-April 1970.  Can´t be more accurate without better astrometry.

    Incidentally, http://www.icq.eps.harvard.edu/bortle.html is an invaluable resource.  I use Norton’s 2000 to convert Bortle’s constellation names into approximate RA/Dec for comparing with plate solutions given by Lars.

    #581806
    David Swan
    Participant

    Peter, I’ve had a look in Sky Safari and you are right.

    P2, the brightest star in the frame is Segin, epsilon Cas

    P3, ” ” gamma Cas

    P4, ” ” gamma Cas

    Nicely placed comets! 

    #581807
    Nick James
    Participant

    I’ve updated the article with the results so far. Great stuff.

    Nick.

    #581811
    David Swan
    Participant

    I suggest this is 96P/Machholz 1 at approx 1970/06/04 23:00 UT 

    #581812
    David Swan
    Participant

    I suggest this is C/1956 R1 (Arend-Roland) at approx 1957/05/20 01:00 UT. Sky Safari places the comet at that time 07 04 55 +63 26 46 J2000.

    #581813
    David Swan
    Participant

    Following on from Paul:

    I suggest this is C/1969 Y1 (Bennett) at around 1970/04/12 02:00 UT.

    #581815
    Paul Leyland
    Participant

    Good to see someone is checking my work to guard against errors. I should do the same for that of other workers.

    My earlier post gave a time of 1957-May-19 21:35.  Agreement is satisfactory.

    #581816
    Lars Lindhard
    Participant

    This was funny.

    Astrometric.net was a fine tool, and I have passed some time today checking (=finding)  the positions on Atlas Stellarum.

    I look forward to the final results form the pro guys.

    A merry christmas to all.

    #581817
    David Swan
    Participant

    8P/Tuttle in Nov 1966?

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