Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 05/09/2020 - 15:37
AKA BSM_Hamren
I have received images of the R CrB field from May 6, 2020.
Pointing, tracking, and focus are good. The primary target (R CrB) is shown as saturated in the B and V images, but it's okay in I. There is a consisten E-W gradiant in all the images. Maybe clouds or a flat problem.
Phil
What about full moon, Phil? Reflection from nearby surface?
Ken
PS: Do plan exposures need adjustment?
Ken,
I went back and looked at the images again. I hadn't noticed that the Hamren images are displayed with N at left and E at bottom. The gradient is actually N-S.
At the time the images were taken the moon was ~52 degrees SW of R CrB. I suppose moonlight could be bouncing off of somthing, but I'd suggest that Hamren images be examined for gradients again during lunar dark time.
Yes, for the R CrB field the V and B exposures need to be reduced since R CrB is saturated in those filters. However, I am already getting good images for R CrB almost every day from NM2 or NH2, and I don't think my getting more images for R CrB would be useful.
Please let me know if you expect to send someone else R CrB images from Hamren, and I'd be happy to recommend some changes to the exposures.
I'm also getting images from Berry for GU Sgr and ASAS-RCB-8, but those images don't come as frequently as I would hope. ...probably weather. If you have time on Hamren I would be happy to get more images of GU Sgr and ASAS-RCB-8.
Phil