It's that time of year that our favorite calibration targets, M67 and NGC 3532, are conveniently in the evening sky. You all have heard how important it is to transform your photometric observations: it makes our data more valuable. So let's all do it! Take a look at the lead post in the past campaign forum thread : We have the tools and training materials to make this process accessible to all.
And... And we have a special incentive for observers to try their hand at transformation: participants will be entered in a raffle to win $500 generously donated by members of the AAVSO!
To become eligible:
1) Report your B and V band transform coefficients (Tv_bv and Tb_bv (eV and eB for you Pep guys cause you can play too) ), along with the method you used to determine them, to this forum. Include the make/model of your OTA, filters, and camera. If you already have coefficients in hand from June of 2016 or later, they are acceptable. And it doesn't have to be M67 that you use: M11, NGC 1252 and NGC 3532 in the South are now all available with reference data for your calibration.
2) Submit transformed B and V magnitude pairs acquired between today and May 15, 2017 (JD 2457889.0) for at least ten stars. Data must be received in WebObs by May 31, 2017, local time.
Observers world-wide are eligible (a winner outside of the US will be paid with an international money order in US funds).
Good hunting!
With my SSP5 photometer having Optec filters mounted on a C9.25:
eV= -0.066
eB = -0.008
and, for fun, k"B = -0.053
M67 Transforms - C-11 @ F/6.0, SBIG ST-10xme Astrodon IVB filters (have R filter, but its an old Schuler glass filter with probable "hazing"). Performed instrumental magnitudes using Vphot from M67 data taken 30-Jan-17, reduced in Transform Generator V6.0. These transforms coefficients are applied to my photometic variable observations using Transform Applier V2.49:
Tbv 1.469 +/- 0.032
Tb_bv 0.316 +/- 0.012
Tv_bv -0.002 +/- 0.014
Tri 1.018 +/- 0.026
Tv_vi -0.001 +/- 0.018
Ti_vi -0.031 +/- 0.024
The transform coefficient are changing very little from the one dozen or so I've taken over the last 3 years. The biggest change comes from doing them from a remote dark sky site at 8000 foot elevation, but most of my data is taken at 400 foot elev, about 10 miles east of downtown Los Angeles!
James
Meade 14" SCT/F10, SBIG STL-1001E. Custom Scientific B and V filters. Instrumental magnitudes using Vphot from NGC 7790 data taken Fall 2016 at the observatory ele. @9000 ft., reduced in Transform Generator V6.0. Transform coefficients are applied to my photometic variable observations using Transform Applier V2.48. I plan on doing another transform on M67 soon.
Tbv 1.307/error .0050
Tb_bv .1430 error .0100
Tv_bv -0.0770 error .0200
I'm trying to compute my transformation coefficients using two different techniques so that I can cross-check against each other. One technique uses VPHOT, but is there a "trick" to getting VPHOT to load the M67 standards sequence? I have a "normal" variable star field image loaded into VPHOT and click "Load AAVSO Comp Stars" and the comparison sequence loads for that star. I put an image of NGC 7790 into VPHOT and click "Load AAVSO Standard Stars" and the standards sequence loads for NGC 7790. I put an image of M67 into VPHOT and click "Load AAVSO Standard Stars" and I get an error message: "Comp stars/sequence exist, but none was imported due to no photometry for this particular filter, or too faint to be detected.0X17378DB". I'm using the same filter name for all the images ("V", although maybe with some trailing spaces).
What could I be doing wrong?
- Mark
Never mind. I figured it out. It was a FITS keyword problem. (Turns out that the default units for CDELT1 and CDELT2 is deg/pixel, not arcsec/pixel as I had assumed. This caused VPHOT to calculate a totally outlandish field of view, which caused all kinds of problems.)
- Mark
OTA = Meade LX200 10" SCT
Filters = BVRI from Astrodon
Camera = SBIG ST-9
Software: IRAF (appphot) + TG V5.10 (checked against VPHOT + TG V5.10, but got smaller residual errors with IRAF)
Field: M67, imaged on 12March2017
Tbv: 1.009 +/- 0.009
Tb_bv: 0.022 +/- 0.010
Tv_bv: 0.002 +/- 0.010
Tvr: 1.088 +/- 0.015
Tv_vr: 0.005 +/- 0.020
Tr_vr: -0.092 +/- 0.021
Tri: 0.939 +/- 0.019
Tr_ri: -0.116 +/- 0.025
Ti_ri: -0.038 +/- 0.026
Tvi: 1.009 +/- 0.010
Tv_vi: 0.001 +/- 0.011
Ti_vi: -0.012 +/- 0.011
Tr_vi: -0.052 +/- 0.011
- Mark
Hi Mark:
Could you clarify whether the filters are older colored glass filters or newer coated filters?
It would also be nice to see how the two software alternatives (IRAF and VPhot) compare. Could you provide the VPhot results also?
Ken
Ken:
The filters are coated and fairly new (2-1/2 years old?).
The transforms that I got using VPhot photometry are (these were from the exact same set of M67 images as I used with IRAF):
Tbv: 1.014 +/- 0.017
Tb_bv: 0.005 +/- 0.015
Tv_bv: -0.016 +/- 0.010
Tvr: 1.073 +/- 0.019
Tv_vr: -0.031 +/- 0.020
Tr_vr: -0.098 +/- 0.020
Tri: 0.942 +/- 0.027
Tr_ri: -0.117 +/- 0.023
Ti_ri: -0.075 +/- 0.033
Tvi: 1.011 +/- 0.016
Tv_vi: -0.019 +/- 0.011
Ti_vi: -0.029 +/- 0.014
Tr_vi: -0.053 +/- 0.010
The coefficients themselves match fairly well. The biggest difference is with Tv_vr which was +0.005 using IRAF photometry and -0.031 using VPHOT photometry.
- Mark
System: CMOS camera (ZWO ASI174MM), BVRI filters (mounted in Xagyl FW) attached to a SkyWatcher 150 mm f/5 Newtonian reflector. (Total cost ~ $2000)
Filters: B: Baader Johnson B filter (interference coating), 4 mm thick.
V: Wratten #12 dye-in-glass cemented to a Schott BG39 dye-in-glass, total thickness ~ 3.5 mm
R: Wratten #23A dye-in-glass cemented to a Schott KG3 dye-in-glass, total thickness ~ 3.5 mm
I: Schott RG9 dye-in-glass, 3 mm thick
Standard stars measured: AAVSO standards in NGC 3532 and 1252 (plus a few Cousins E-region standards) on 2 photometric nights (suitable for all-sky photometry).
Average of measurements for 2 nights:
Tb_bv = -0.118
Tv_bv = -0.055
Tr_vr = -0.134
Ti_vi = 0.001
Tbv = 0.933
Tvr = 1.049
Tvi = 0.961
Ideally want T for magnitudes between -0.1 and 0.1 and T for colors between 0.9 and 1.1. Measurements suggest V and I filters are 'well-matched' while Baader Johnson blue filter ($200+) and bespoke R filter are not as 'well-matched'.
My coefficients were obtained by imaging M67 on 3/16/2017. OTA: Meade 0.4M SCT @f/8. Camera: FLI Proline 1kx1k back-illuminated CCD chip. Filters: Astrodon BVRI. Transformation Generator v6.0 used.
Barbara Harris (HBB)
This is my first try at calculating transformation coefficients. I hope I did everything correctly. My B-b vs B-V (and also V-v vs B-V) regressions are not nearly as good as what is shown in the examples (Fig 6.5 of CCD photometry guide : https://www.aavso.org/sites/default/files/publications_files/ccd_photom…). Is this normal? Everything else looks fine (with nice linear regressions between my instrumental magnitudes and the standard values).
Anyways, treatement and photometric analysis was done with IRIS, on 13 stars in the M67 field (mostly stars outside the cluster because of my low resolution).
Setup: Atik 414ex on Orion ED80 (80/480 refracting scope). Filters: Astrodon Photometrics UBVRcIc (almsot brand new, I bought these in December 2016).
All images were taken on March 16, between 02:10am and 02:45am UTC from Bloomington, IN (USA) in a heavely light-polluted environment. 30 to 75 images per filter processed and stacked with IRIS.
Tbv
1.301655
Tvi
1.004298
Tvr
1.132687
Tb_bv
0.145654
Tv_bv
-0.08609
Ti_vi
-0.08063
Tr_vr
-0.26744
If I have another clear night by APril 15th I'll try to do the same for my C8 and maybe also try to replicate the results with the ED80 and compute some average values across two independent measures.
jf
Thanks for the encouragement to (finally) do this. Below are the results for the Burke-Gaffney Observatory (Nova Scotia) based on one observation set taken on March 12. I'll run it again soon to see how consistent it is.
The TG program was easy to figure out and use - thanks to the developers. I did the photometry in MaxIm. I dropped outlier stars 14, 30 (i issues), 38 and 51 (stars close together).
Any comments on how this transform looks are welcome!
[Coefficients]
[Error]
[R Squared Values]
Tbv= 1.023
Tbv= 0.006
Tbv= 0.999
Tb_bv= -0.005
Tb_bv= 0.006
Tb_bv= 0.021
Tv_bv= -0.028
Tv_bv= 0.005
Tv_bv= 0.471
Tvr= 1.031
Tvr= 0.009
Tvr= 0.997
Tv_vr= -0.056
Tv_vr= 0.009
Tv_vr= 0.466
Tr_vr= -0.086
Tr_vr= 0.011
Tr_vr= 0.604
Tri= 0.971
Tri= 0.014
Tri= 0.992
Tr_ri= -0.103
Tr_ri= 0.013
Tr_ri= 0.595
Ti_ri= -0.073
Ti_ri= 0.019
Ti_ri= 0.251
Tvi= 1.002
Tvi= 0.008
Tvi= 0.997
Tv_vi= -0.030
Tv_vi= 0.005
Tv_vi= 0.454
Ti_vi= -0.032
Ti_vi= 0.009
Ti_vi= 0.236
Tr_vi= -0.047
Tr_vi= 0.006
Tr_vi= 0.601
Cheers, Dave
here are my M67 averaged coefficients from TA. Images from 12-16-16
[Setup]
ObsLon=-88 32 43
ObsLat=41 44 41
description=M67all_cleaned_8inSCT_ST8XME
Dir=
[ExtinctionError]
Eu=0
[Coefficients]
Tbv=1.23500001430511
Tbr=0
Tb_bv=0.150999993085861
Tv_bv=-0.0419999994337559
Tvi=0.980000019073486
Tv_vi=-0.0480000004172325
Ti_vi=-0.0270000007003546
[Error]
Tbv=0.0329999998211861
Tb_bv=0.028999999165535
Tv_bv=0.0179999992251396
Tvi=0.0219999998807907
Tv_vi=0.0219999998807907
Ti_vi=0.0280000008642673
[Extinction]
Eb=0.368000000715256
Ev=0.214000001549721
Ei=0.129999995231628
Eu=0
Er=0.165000006556511
apply=1
WebOBS shows 20 AAVSO variables, all one~20' field, ranging from 8m to 13m with skimpy errors taken from VPHOT on JD-2457830. Most are sparse in the AAVSO DB. VPHOT averages of 5 or 6 mug shots at A.M.~1.6. Not ideal but most are usable.
Gobs more to come if I can find time to reduce and transform it all.
VPHOT, TG, TA all very useable. MaxIm DL for imaging, solving, and image calibration. OTA is old Meade 8" SCT. Camera is used (shutter has >>500,000 openings) ST8XME. BVI filters are Custom Scientifics. All images visually inspected.
RayTRE
Also using NGC 3532 (thank you for providing) which is nice and high around midnight at the moment at 32° south.
Image train - DSI RC14C telescope, Astrodon B & V filters and a [very old} SBIG ST-10.
21 stars run through MaxIM DL, and using TG Version 6 - a positively luxurious experience compared to using the old manual spreadsheet method. Thank you developer(s).
Tbv = 1.016
Tb_bv = 0.028
Tv_bv = 0.012
Paul
PS - quick question. Does TG average multiple data automatically? Ie, in my case 5 x 3 second V images plus 5 x 8 second B images in my CSV file.
Paul,
Yes, TG automatically averages multiple measurements of each star.
Gordon
I've noticed some of you like DKS have been succesfull
Doing transforms with ensemble measurements. I've heard this is tricky, but how is it accomplished?
In VPhot: You must first enter your transforms in the Admin>telescope setup section. You must also have a "saved" comp star sequence for the target. . In most cases you would use the AAVSO comp star sequence for the target, but you must save and name the sequence in the image display for one of the images.
First load one of your images. From the Catalogs box load the VSX stars and also the AAVSO comp star sequence. Name and save this sequence from the small box at the upper left of the image display. Your saved sequence must include the target and (I believe) a check star. You then go back to the images list.
Let's say you have transforms for B-V. From the images list, click in the selection boxes for the B and V images of the photometry ensemble images you want transformed. Then, from the menu options, just above the images list, click "transform". In the first "Color photometry" page, select the name of the sequence you saved for this target. The next page will show the transformed B and V magnitudes for your target(s) and the check star.
Phil
Here are mine, using an Optec SSP5 with Optec Filters mounted on an Tinsley 10" Cass.
eV= -0.0918, eB= 0.031, muB= 1.140
Paul W. Kneipp (KPL), Bayou Astronomical Observatory,
M67 vphot=>TG ver 5.10
OTA: Celestron Edge HD1400
Filters: Astrodon B***_50R, V*_50R, Rc*_50R, Ic*_50R
Camera: SBIG STXL-6303E
Images date: 2017-03-10 JD2457831.635
Filter Band Coefficients
T = 0.136 Band: B Color Index: B V
T = 0.003 Band: V Color Index: B V
T = -0.001 Band: V Color Index: V R
T = -0.083 Band: R Color Index: V R
T = -0.069 Band: R Color Index: R I
T = -0.101 Band: I Color Index: R I
T = 0.006 Band: V Color Index: V I
T = -0.021 Band: I Color Index: V I
T = -0.039 Band: R Color Index: V I
Colorindex Coefficients
T = 1.131 Color Index: B V
T = 1.100 Color Index: V R
T = 1.058 Color Index: R I
T = 1.046 Color Index: V I
Cliff Kotnik
Hi everyone,
Thanks Ken Menzies (as usual for the huge help!)
Also, the user guides are very clear for a newbie like me.
Field: NGC3252. Vphot (stack method) for reports, then TG ver 6.0 on Windows (~190 stars)
OTA: SkyWatcher 250 f/4.7
Filters: Astrodon (Gen 1) V, B, Sloan i and Sloan r (transformed to R and I)
Camera: Apogee Alta U8300 in bin2x2
Date: 2017-04-18 JD2457857.494
Coefficients:
Tbv
1.000+/-0.005
Tb_bv
-0.007+/-0.007
Tv_bv
0.005+/-0.007
Tvr
1.307+/-0.008
Tv_vr
0.024+/-0.013
Tr_vr
-0.197+/-0.010
Tri
1.025+/-0.016
Tr_ri
-0.214+/-0.012
Ti_ri
-0.314+/-0.020
Tvi
1.160+/-0.010
Tv_vi
0.013+/-0.007
Ti_vi
-0.145+/-0.011
Tr_vi
-0.105+/-0.006
Emilio
Here ae my transformation coefficients:
epsilon V =-0.0391
epsilon B=0.1038
My second order extinction coefficient in B is k''B=-0.037
Most recently I used the red/blue pair in Leo Minor (LMi 27 and 28) to calculate the two transformation coefficients as well as the second order extinction. I use a Celestron C14 and an Optec SSP3 Gen II for my photometric system.
Given my recent weather and the time required for each two color PEP measurement I probably won't meet the 10 star deadline but I will give it a shot. Wishing everyone clear skies.
Jim
Frames: M67, 9 frames for each filter (UBVRI), taken on 3/27/2017, 3/25/2017, and 3/24/2017.
Scope: AGO 12.5" iDK
Filters: Astrodon 1.25" UBVRcIc (all but V purchased last summer)
Camera: SBIG ST8-XME
I used VPHOT to do the photometry on the M67 images, and then used Transformation Generator 6.0 to calculate the transform set. I think this set of transforms is better than the ones I originally did back in Nov. 2016 - the values are similar, but the error is much less since I think I did a better job of removing bad stars/points from the model. Since the values are slightly different than before I think I'll do another set in the future, but maybe try a different standard field to compare.
Tub = 1.278 +- 0.008
Tu_ub = 0.195 +- 0.005
Tb_ub = -0.017 +- 0.002
Tbv = 0.971 +- 0.003
Tb_bv = -0.037 +- 0.003
Tv_bv = -0.014 +- 0.003
Tvr = 1.050 +- 0.007
Tv_vr = -0.023 +- 0.006
Tr_vr = -0.103 +- 0.004
Tri = .983 +- 0.007
Tr_ri = -0.130 +- 0.004
Ti_ri = -0.069 +- 0.006
Tvi = 1.005 +- 0.003
Tv_vi = -0.013 +- 0.004
Ti_vi = -0.061 +- 0.003
My transform coefficients are listed below.
Field: NGC3252
OTA: Orion ED80T CF 80mm f6 refractor, with field flattener
Filters: Astrodon B, V, R, I
Camera: SBIG STT-3200ME binned 1x1
Method: 5 images through each filter, stacked in VPhot, 92 standard stars used to calculate transform coefficients with latest version of TG (6.0)
Date: First image recorded 2017-04-24 JD2457867.944, last image JD2457867.952
Coefficients:
Tbv
0.992+/-0.010
Tb_bv
-0.007+/-0.012
Tv_bv
0.015+/-0.006
Tvr
1.039+/-0.010
Tv_vr
0.033+/-0.011
Tr_vr
-0.004+/-0.010
Tri
0.909+/-0.013
Tr_ri
-0.004+/-0.011
Ti_ri
-0.096+/-0.023
Tvi
0.972+/-0.010
Tv_vi
0.018+/-0.006
Ti_vi
-0.046+/-0.011
Tr_vi
-0.002+/-0.005
So far some 16 users have submitted their new transform coefficients to this forum for the contest. But, only 4 have submitted transformed observations of 10 stars, a requirement of the contest. So you other 12, grab your list of bulletin stars and get observing! You have until May 15 to observe!
Good luck!
Hi!, Celestron C14 Edge HD, SBIG STF8300,Astrodon B,V
M67 10 stacked each using Vphot. and the AAVSOTransform Generator software
Tbv=1.286 err=.023
Tb_bv=0.178 err=.007
Tv_bv= -0.044 err 0.013
Best!
Pablo Lewin
Field: M67
Filter set: Astrodon dielectric B & V
Scope: Meade LX200-14
CCD: SBIG STT-8300M
Method: Stack of 10 images each in B & V, processed with TransformGenerator 5.5
Transform coefficients:
Tb_bv = 0.025 +/- 0.005
Tv_bv = -0.028 +/- 0.002
Tbv = 1.058 +/- 0.005
Shawn Dvorak (DKS)
Clermont, FL
Transformation Coefficients for: Kiowa Creek Observatory (KCO)
Standard Field: M67
Date: 2017 Mar 04
JD: 2457816.77308
OTA: Meade 30 cm SCT
Camera: SBIG ST8-XME
Filters: Astrodon BVI
Multiple images calibrated then average stacked in vPhot.
Instrumental magnitudes using Vphot.
Coefficients generated by Transform Generator V6.0.
Transform coefficients applied in VPhot (Admin/Telescope Setup - Transformation Coefficients)
Filter Band Coefficients
Tb_bv = 0.038 +/-0.025, Band: B Color Index: B-V
Tv_bv = -0.030 +/-0.017, Band: V Color Index: B-V
Ti_vi = -0.087 +/-0.030, Band: I Color Index: V-I
Tv_vi = -0.041 +/-0.019, Band: V Color Index: V-I
Color Index Coefficients
Tbv = 1.065 +/-0.027, Color Index: B-V
Tvi = 1.040 +/-0.020, Color Index: V-I
BV observations on 2 stars and BVI on 4 for a total of 6 stars so far. Weather prospects from now until the 15th don't look good, but I'll remain optimistic that I can get obs on 4 more stars by then.
Scott Donnell
Here are my transformation coefficients for a small 66/400 Skywatcher Equinox refractor with Orion G3 monochrome CCD. Astrondon Johnson B and V filters. Based on 10 cleanly separated brighter stars in M67 field, as the pixel scale is ~4.3 sec/pixel and a little coarse. 8 images in each filter taken on 2017-04-16. Photometry and transforms calculated using GCX-1.5 (open source software developed by Radu Corlan).
Tb_bv = 0.052 +/- 0.004
Tv_bv = -0.031 +/- 0.003
Tbv = 1.067 +/- 0.005
Now if I could get a couple more clear nights before the 15th!
Cheers,
Mark
Here are the transforms for my 0.43 m CDK PlaneWave with Astrodon (with improved B filter blocking) filters:
Tbv 1.041+/-0.017
Tb_bv 0.030+/-0.014
Tv_bv -0.009+/-0.008
Method: Three images in each band of M67 reduced with VPhot and TG (Thanks Gordon) using a SBIG STL-1001 camera
Richard Sabo
Perhaps I missed it, but has a winner been announced?
At the SAS meeting the winner of the 2017 Transform Campaign was announced:
Congratulations Shawn Dvorak!
Some 22 people participated and 7 observers fully qualified for the prize.
Thank you all for participating and moving your workflow up that extra notch to start submitting transformed data to the AID.
If I may ask, who were the seven who qualified?
The 7 finalists were: Barbara Harris, Paul Luckas, Shawn Dvorak, Ray Tomlin, Michelle Dadighat, Mark Munkacsy, Scott Donnell.
One person randomized the list and another asked google for a random number, 1 to 7.
George
I'll put the money to appropriate use: I'll buy an I (infrared) filter to add to my BVR set.
Hopefully, this will bring in more transformed measurements. I do a lot of unfiltered observations of faint objects for the CBA, but for bright objects I generally try to get both B and V measurements, at least for stars where the color index is interesting.
Shawn
Mine was posted back in March and done again later with out posting and used for observations since. --- Dave LDJ