Affiliation
American Association of Variable Star Observers (AAVSO)
Sun, 10/07/2012 - 03:09
I have been observing V1404 CYG for several nights. Comparing to the LCG, I was 1-3 magniutudes too faint. I remembered that the target could be mistaken by a nearby star. I collaborated with Jim Roe and Richard Sabo, and they compared their observations with the finder chart, and confirmed that they had also mistaken the target, as I had on my first attempt.
If you observed V1404 Cyg lately, check to make sure you are using the third star in the row of 3 and not the 2nd star in the row of 2. We have changed our observations, or are in process of doing so.
THanks
Gary Walker. WGR
Downes and Shara identify this variable as the middle of the three extremely close stars in a line, as in this 5'x5' image from the D&S website.
http://archive.stsci.edu/prepds/cvcat/query_processor.cgi?setup_file=va…
As far as I can recall this is the star I have been reporting as V1404 Cyg.
You do have to be careful when using VPHOT on faint targets. it will often apply the aperture to the nearest brightest star dot, not necessarily the correct one. That is one reason I do those kind of objects manually. You may also need to reduce the sice of the aperture to exclude nearby comps or to get VPHOT to "stick" to the proper star.
As Arne pointed out to me this morning, the very faint stars in the trio of stars (NE-SW) I was refering to probably don't show up in most AAVSO observer's images, so V1404 Cyg would appear to be the third star in a line of three going from SE- NW.
If you plot an F or G scale chart in VSP it does identify the proper star rather unambiguously.
For me, with a 12 inch scope, the target barely shows up in a 3 minute exposure and just shows up in a 5 minute exposure. I have not used VPHOT on this one. Using Maxim, so the identification is done manually and I first did identify the middle star of the 3(when I could only see 2), but then looked carefully at a G chart, and saw that I had selected the middle star of the 3. Its an easy mistake to make manually, I was not aware of the VPHOT issue, thanks for pointing it out.
I do suspect that we have several observers using the wrong target. Both Sabo and Roe have agreed and removed their PT and are doing it again, and will repost.
Any other observers find the same thing?
Gary