BSM_Berry2 Transformation Coefficients

Affiliation
American Association of Variable Star Observers (AAVSO)
Fri, 11/20/2020 - 16:48

Transformation coefficients for BSM_Berry2 were generated on 201120. The coeffs are shown below. They have been added to the BSM_Berry2 telescope settings in VPhot and are used in VPhot color photometry.

Note that Berry2 uses a Sloan R filter rather than a Cousins R filter. These coeffs transform SR magnitudes to Cousins R magnitudes and they should be reported as such.

Ken

[Setup]
description= TG - Version 6.6, Telescope= BSM_Berry2, Time created (UT) = 2020_11_20_16:41:07
[Coefficients]
Tbv= 1.097
Tb_bv= 0.059
Tbr= 1.128
Tb_br= 0.039
Tb_bi= 0.030
Tbi= 1.031
Tv_bv= -0.025
Tvr= 1.197
Tv_vr= -0.042
Tr_vr= -0.203
Tri= 0.818
Tr_ri= -0.214
Ti_ri= -0.006
Tvi= 0.977
Tv_vi= -0.016
Ti_vi= -0.003
Tr_vi= -0.107
[Error]
Tbv= 0.020
Tb_bv= 0.013
Tbr= 0.012
Tb_br= 0.008
Tb_bi= 0.007
Tbi= 0.007
Tv_bv= 0.010
Tvr= 0.020
Tv_vr= 0.020
Tr_vr= 0.016
Tri= 0.009
Tr_ri= 0.016
Ti_ri= 0.014
Tvi= 0.009
Tv_vi= 0.011
Ti_vi= 0.007
Tr_vi= 0.007
[R Squared Values]
Tbv= 0.994
Tb_bv= 0.643
Tbr= 0.998
Tb_br= 0.678
Tb_bi= 0.616
Tbi= 0.999
Tv_bv= 0.175
Tvr= 0.991
Tv_vr= 0.129
Tr_vr= 0.839
Tri= 0.997
Tr_ri= 0.879
Ti_ri= 0.007
Tvi= 0.997
Tv_vi= 0.092
Ti_vi= 0.009
Tr_vi= 0.876

Affiliation
American Association of Variable Star Observers (AAVSO)
Coefficients in Vphot

I was working on a star and the transformed B-values for my target seemed way off and inconsistent with values I measured with OC61. The B-V for my target was about 1 to 1.1 redder than expected and the measured B-values on several check stars were all about 1 magnitude dimmer than catalog values. 

My SNR was great and the images looked good. 

Then I noticed the Tbv coefficient pre-loaded on the two color transform page was 2.814 and thought that didn't seem right. From checking here, I see that its not. When I manually changed this value to 1.097 as listed here, my check stars all agree with catalog values and the B-V on the target is consistent with expectations. 

I can't change (or at least it doesn't look like I can change) the coefficients for this telescope. They also are different than what ended up being loaded in the two color transform screen. 

I think the transform coefficients loaded into VPHOT need to be looked at for this scope to make sure they're entered right and/or there isn't a glich in VPHOT. 

Affiliation
American Association of Variable Star Observers (AAVSO)
Coefficient Discrepancy

Rich:

Your observations are disturbing! However, I cannot reproduce your finding by looking at the coefficients for Berry or Berry2 or Berry4. I do find a discrepancy but not the one you found?

Can you share (MZK and SGEO) the images you were using and can you share a screen shot of the two color page with the Tbv =2.814 coeff?

Email to kenmenstar@gmail.com and gasilvis@gmail.com

Ken

Affiliation
American Association of Variable Star Observers (AAVSO)
System Name Error

Rich:

This error has been fixed as we discussed in separate emails. The error was caused by an error in the SystemName for Berry2. I have updated the coeffs in this post and in VPhot.

Ken 

Affiliation
American Association of Variable Star Observers (AAVSO)
BSM_Berry2 Transformation Coefficients 201202

Transformation coefficients for BSM_Berry2 were generated on 201202. The coeffs are shown below. They have been added to the BSM_Berry2 telescope settings in VPhot and are used in VPhot color photometry.

Note that Berry2 uses a Sloan R filter rather than a Cousins R filter. These coeffs transform SR magnitudes to Cousins R magnitudes and they should be reported as such.

Ken

[Setup]
description= TG - Version 6.6, Telescope= BSM_Berry2, Time created (UT) = 2020_12_02_23:22:47
[Coefficients]
Tbv= 1.066
Tb_bv= 0.013
Tbr= 1.097
Tb_br= 0.008
Tb_bi= 0.006
Tbi= 1.012
Tv_bv= -0.017
Tvr= 1.189
Tv_vr= -0.016
Tr_vr= -0.189
Tri= 0.814
Tr_ri= -0.202
Ti_ri= 0.021
Tvi= 0.971
Tv_vi= -0.009
Ti_vi= 0.013
Tr_vi= -0.098
[Error]
Tbv= 0.019
Tb_bv= 0.010
Tbr= 0.012
Tb_br= 0.007
Tb_bi= 0.005
Tbi= 0.007
Tv_bv= 0.015
Tvr= 0.022
Tv_vr= 0.027
Tr_vr= 0.027
Tri= 0.014
Tr_ri= 0.027
Ti_ri= 0.009
Tvi= 0.013
Tv_vi= 0.014
Ti_vi= 0.007
Tr_vi= 0.013
[R Squared Values]
Tbv= 0.990
Tb_bv= 0.048
Tbr= 0.996
Tb_br= 0.042
Tb_bi= 0.036
Tbi= 0.999
Tv_bv= 0.038
Tvr= 0.990
Tv_vr= 0.013
Tr_vr= 0.630
Tri= 0.991
Tr_ri= 0.658
Ti_ri= 0.232
Tvi= 0.995
Tv_vi= 0.014
Ti_vi= 0.131
Tr_vi= 0.648