Affiliation
American Association of Variable Star Observers (AAVSO)
Sun, 05/24/2020 - 03:09
Hi all,
I've been looking for OC61 TC's and can't find them anywhere.
Lots of SI and SR observations that could be useful for an observing program I've got running.
A brief search for these turned up people looking for the same thing.
Thanks!
-Chris
AAVSO Ambassador
Chris;
I installed a plan for Std Field NGC 3532 onto the scope. Should get some images (B,V,SR,SI) soon? SR,SI will be transformed to Cousins R,I. Would you like to generate coeffs with TG?
Ken
Hi Ken,
Thanks so much for working this.
Yes, lets go ahead and use TG to generage the coeffiecients.
Thank you again!
-Chris
I see that OC61 has three recent nights of images for Std Field NGC 3532. If someone calculates TCs for this scope, please post them here. Whose folder are these images in on the FTP site?
Thanks,
Bob
Bob:
When I have generated the TCs they will be posted on the AAVSONet Forum as a sticky post as all other scope TCs are.
Currently, the recent images of NGC 3532 do not have appropriate exposures so I'm taking more.
If you want to play with the poor images and generate your own TCs for personal use, I can share the images with you?
Ken
Ken,
I'll wait for your meaurements.
Does NGC 3532 have enough redder stars to measure good TCs?
Bob
Bob:
Good is in the eye of the beholder! This Std Field is only marginally adequate (IMHO) since it is really a wide field of view (45') and a bit sparse for this 0.61m scope (14').
Right now,with inappropriate exposures, I only get about 20 comps. The color range is still reasonable.
A first test gives the following TG plots and coeffs (just 3). I am trying more runs before I make then official. Note that the filters are SR and SI but the coeffs will transform to Cousins R and I.
Ken
[Setup]
description= TG - Version TG_V7.4, Telescope= OC61, Time created (UT) = 2020_06_04_14:54:03
[Coefficients]
Tbv= 1.010
Tb_bv= -0.059
Tv_bv= -0.042
Tvr= 1.041
Tv_vr= -0.081
Tr_vr= -0.166
Tri= 0.983
Tr_ri= -0.181
Ti_ri= -0.154
Tvi= 1.005
Tv_vi= -0.043
Ti_vi= -0.078
Tr_vi= -0.087
[Error]
Tbv= 0.015
Tb_bv= 0.013
Tv_bv= 0.012
Tvr= 0.038
Tv_vr= 0.022
Tr_vr= 0.040
Tri= 0.017
Tr_ri= 0.044
Ti_ri= 0.047
Tvi= 0.021
Tv_vi= 0.007
Ti_vi= 0.024
Tr_vi= 0.021
[R Squared Values]
Tbv= 0.995
Tb_bv= 0.511
Tv_bv= 0.390
Tvr= 0.973
Tv_vr= 0.438
Tr_vr= 0.470
Tri= 0.994
Tr_ri= 0.474
Ti_ri= 0.377
Tvi= 0.991
Tv_vi= 0.709
Ti_vi= 0.351
Tr_vi= 0.472
OC61 coefficients have been generated and placed in VPhot telescope setup. They are provided in a sticky post in the AAVSONet forum.
Ken
Ken,
Thanks for all your work on this. I notice there was a considerable change in the Tbv and Tv_bv TCs between the preliminary numbers you posted on 6/4 and the ones posted on 6/8. Will any additional nights be collected to further improve the numbers?
Thanks,
Bob
Bob:
As I had noted, the coeffs from 6/4 were not good. The subsequent two nights used much better exposures and no saturation occurred.
The coeffs I posted in the Sticky Post are an average of multiple images on two separate nights. They are usable.
Ken
Hi Ken,
How would you recommend getting comps for targets since vPhot believes it's trying to pull SI and SR comps that don't exist. Should I just request Ic and Rc comps?
Thanks.
Chris:
1. IF you are going to transform your image magnitudes, rename the SR and SI filters to R and I respectively. You will get R and I magnitudes when you request AAVSO comps under Catalog and you can save them in your sequence. For 2 color transform photometry, the coefficients that come up are those necessary to transform the Sloan SR and SI magnitudes to the Cousins R and I magnitudes. That is how I generated them. Report them as the latter.
2. IF you are NOT going to transform, you need to find SR and SI magnitudes for your comp stars from SeqPlot and list them in your sequence magnitude list. Report them as untransformed SR and SI magnitudes.
Ken
Ken,
In vPhot, the transforms in Two-Color Transform for V-SI and V-SR are blank along with the B-SI and B-SR... it doesn't appear there is a way for me to transform them to Rc or Ic.
Also, how do I rename the filters in vPhot since they were already uploaded from the telescope as SI and SR? I get in order to report them as transformed I may have to edit the report file, but I have no idea how to edit the filters within vPhot.
Thank you.
Just figured out how to change the filters and this fixed my other issue as well.
Sorry for the trouble!