Numerous papers say the precursor to Nova Cyg 1975 is visible on a Palomar Sky survey blue plate. The precursor is not visible on the online version of the blue plate, so I assume the precursor was found by examining the actual blue plate and not a print or digital scan of the plate. Anyway, for a presentation I want to do for my local astronomy club, I’m interested in finding a photo that someone may have taken of the actual plate that shows the precursor. Any ideas on who to contact?
Looking at the POSS-I blue plate-scan available from the Goddard SkyView utility, the precursor does seem to be just visible, about blue mag 20. I’m searching now for a better scan from the USNO-Flagstaff PMM machine, which made use of the original plates rather than copies.
\Brian
The link to the PMM machine scans is a bit hidden and not public, and in any case the image is not any better than the one you can get from Goddard SkyView. At the latter site, I’d suggest grabbing a 2’x2’ (0.03-deg) cut-out of all the ‘Optical:DSS’ images with the ‘Stern special’ color scheme and however many pixels is convenient (around 500 or 600 depending on computer screen size/resolution).
\Brian
Thank you, Brian. Not sure if you’re looking at the same area as me but I don’t see anything at the position. I typed in “v1500 cyg” rather than the RA and Dec and it centered the target exactly and there is nothing there that I can see. I turned on the “image center reticle” to confirm.
Thanks for the tip on that site. Was not familiar with it.
Randy
You might find it useful to look at a paper published by Isobe et al. in 1975:
Accurate position of nova Cygni 1975. - ADS
It describes a measurement of the position of the nova, and shows a photograph of the blue POSS I plate with several stars labelled. The photograph doesn’t show much detail, but it might help you to orient yourself when you examine digitized copies of the POSS I plate yourself.
I used Aladin to display a section of the POSS I plate around the nova’s position. The crosshairs at the nova’s position (position supplied by SIMBAD, I think) appear to line up with the object labelled “Star 1” by Isobe et al. They stated that “Star 1” was likely not the nova, but that it was close enough that they couldn’t be sure. My guess is that their “Star 1” is the nova.
When I look at that position on the POSS I plate, I see a very, very faint smudge that is probably a star, but could be a noise peak. It’s hard to say, since the stellar density is so high.
I hope this might help. Good luck!
MWR
I agree with Michael that the Isobe star 1 is “it”. Just a smudge barely above the noise on the POSS-I blue plate-scan, and crowded by the other stars within a few arcseconds.
\Brian
Greetings,
I published a 2x2 arc min. finder for V-1500 Cyg in IBVS #3963 back in 1993 using an image from the USNO 1.55m telescope at Flagstaff. V-1500 Cyg was around 17.8 V at the time. Different filter than the POSS-B. The POSS-B image shows the precursor as just a small blended bump off the main blob of other stars nearby.
Jim (DEY)
Jim: a swell image in your paper that clearly separates the stars - thanks! I imaged the nova in 2016 (amateur photo, no photometry) and plan on doing it again this August for the 50th anniversary of the blast.
That POSS-Blue “hash” seems to be in the correct place, but I’d never suspect a star there if I didn’t know there was supposed to be one. Duerbeck made the claim of a visible precursor on the POSS plate in his ‘Reference Catalogue and Atlas of Galactic Novae’ but I don’t know how he confirmed - by looking at the physical plate personally with a magnifier(?) or other means. Whoever has access to the actual plate - it would be neat to have them take a high res magnified photo of that portion rather than looking at various “scans”. A friend of mine was an astronomy major in '75 (yes, we’re old) and he made a neat 1-page adder on the nova to insert into Burnham’s Celestial Handbook. Anyway, thanks to all respondents - you’ve provided fuel for my astronomy club presentation!
Randy
1 Like
I presume you have used the digitized POSS available for searching here. The STScI Digitized Sky Survey
Using SAOImage ds9 to view the downloaded 2’x2’ patch of POSS1 B digitized image you can see the blended precursor. SAOImage ds9 has excellent image stretching capabilities which allows one to get a stretch that doesn’t have so much contrast. I have marked in green that which matches with the 1993 finder chart! There is another star just a few pixels to the west to confuse things but the one marked must be the precursor identified.
Jim (DEY)
If it’s not processed film grain. No sign of the star to the west on PanStarrs imagery.
The POSS B 103aO film-based bandpass is further blue than any filters used in the PAN-STARRS system. So the “thing” to the west could be noise, could be a PAN-STARRS non-detection.
Jim (DEY)