It's still March, barely, and still time to collect images of M67 with which to prepare your transform coefficients.
Improvements have been made to VPhot to make this easier. Here's how to do it:
1. Collect your images of M67 in all your filters. It's on the meridian at sunset or just past: now is the time to get it done.
2. Upload the images to VPhot.
3. Select all the images, that is, all filters, and the select Time Series. This now works with multiple filters.
4. For sequence you should select "com M67 AUID".
This is the first new feature: common sequences available to all users.
You cannot edit it, though you can copy and edit a copy if you wish.
The second feature is that this sequence has the star labels replaced with AUID's
Time Series requires a target star. This sequence has one, HW Cnc, to satisfy the requirement.
We don't want it other than to allow us to use the Time Series process.
5. Hit Start the Analysis
6. Once done, select General Export
7. At the bottom of that page you will see a button "Save to AIP fmt for TG"
This is the secret sauce: All your M67 photometry is packed into one file that is in a format that TG will accept
8. Open TG, select your scope, M67 and AIP/Maxim format and you're ready to create your transform coefficients
9. When done, don't forget to output the coefficients into an INI file that you can take to VPhot and import into your telescope profile.
This workflow cut the time it takes to go from images to TG by 80% for me. Hope it works for you!
So get out there and take pics of M67!
Cheers,
George
Thanks George!! I had tested the waters recently with TG and TA and was planning to revise my transformation coefficients here the next several days since we are expecting good skies and Mr. Moon has went farther east.
Appreciate the set of numbered steps, that really resonates with my style of learning. I for one will be taking your advice and will be collecting data on M67...
Jamey Jenkins
Good day.
I'm also new in transforming magnitudes. I'm using the Vaonis Stellina smart telescope for testing in doing photometry. It consists of an 80mm ED doublet refractor, 400mm in focal length, and SONY IMX178 CMOS color sensor and which automatically sets-up, plate solve, autofocus, take short-exposure images, and auto-stack them through an app. One cool thing about this is I can retrieve all raw FITS images when I plug in a USB stick to it. More information about it can be found here: https://vaonis.com/stellina
Since the sensor is uncooled one-shot color (TB, TG, TR), I followed through the methodology noted in the DSLR Observing Manual wherein I split the RGB channel images after calibrating and stacked them. Afterwards, I did this exact procedure to get the transformation values; found it simple and easy to follow.
After uploading the generated .ini file, I tried transforming magntiudes for TW Hya from images I captured few weeks ago. However, I got the following error.
Star Date Filter Grp Vraw Vinst Vex TranMag diff VERR VERRt
"TW Hya " 2459291.43303 B 0101 12.300 0.209 0.209 not transformed
"TW Hya " 2459291.43303 V 0101 11.156 -0.864 -0.864 not transformed
"TW Hya " 2459291.43303 R 0101 10.040 -0.715 -0.715 not transformed
Detail narrative for each observation
TW Hya,2459291.43303,12.300,0.033,B,NO,STD,118,0.952,111,-0.124,na,0,X26424V,na
CREFMAG= Bc= 13.043 +/- 0.078 (nb. comp ref error is excluded from final error computation)
STD inst mag: Vinst= 0.209 = 12.300 + 0.952 - 13.043
bc= 0.952 +/- 0.000 (c error is included with VERR)
bs= 0.209 +/- 0.033
Formula error! Check your coefficients!
TW Hya,2459291.43303,11.156,0.018,V,NO,STD,118,-0.177,111,-1.022,na,0,X26424V,na
CREFMAG= Vc= 11.843 +/- 0.013 (nb. comp ref error is excluded from final error computation)
STD inst mag: Vinst= -0.864 = 11.156 + -0.177 - 11.843
vc= -0.177 +/- 0.000 (c error is included with VERR)
vs= -0.864 +/- 0.018
Formula error! Check your coefficients!
TW Hya,2459291.43303,10.040,0.018,R,NO,STD,118,0.513,111,0.150,na,0,X26424V,na
CREFMAG= Rc= 11.268 +/- 0.029 (nb. comp ref error is excluded from final error computation)
STD inst mag: Vinst= -0.715 = 10.040 + 0.513 - 11.268
rc= 0.513 +/- 0.000 (c error is included with VERR)
rs= -0.715 +/- 0.018
Formula error! Check your coefficients!
Summary of group data
name+group filtC Us Bs Vs Rs Is us bs vs rs is
"TW Hya0101 " 7 na 12.215 11.178 10.201 na na 0.209 -0.864 -0.715 na
name+group filtC Uc Bc Vc Rc Ic uc bc vc rc ic
"TW Hya0101 " 7 na 13.043 11.843 11.268 na na 0.952 -0.177 0.513 na
transform coefficients applied by Transformer Applier, version 2.51
desc: TG - Version 6.6, Telescope= STELLINA, Time created (UT) = 2021_04_03_17:25:44
Tbv= 4.9940, +/- 23.0880
Tbr= 2.2400, +/- 0.7360
Tvr= 0.7440, +/- 0.1990
Tb_bv= 0.5270, +/- 0.3140
Tb_br= 0.3570, +/- 0.2110
Tv_vr= -0.3190, +/- 0.7640
Tv_bv= -0.1360, +/- 0.3770
Tr_vr= -0.2000, +/- 0.9980
Any thoughts where did I go wrong here and what can I do to fix this? I'm currently stuck here in this process. Thank you very much in advance. Clear skies.
Aldrin:
The first thing to notice is how large some of your reported +/- errors are (e.g., Tbv 4.9940+/- 23.0880)!
What did your TG plots look like? How many std comps from M67 did you have? Did you deactivate the outliers?
It is possible to save some of the plots as png files. You could provide them and the ini file from TG to George and I via separate email.
Ken
I sent you an email including the plots. I don't know George's email so you can CC him on your reply. Thank you very much.
Aldrin
Good day.
I re-did my acquisition of the transformation values. So far, I got some smaller values compared to the ones posted in the forum. Herewith attached are the images showing the graphs for Tbv, Tvr, and Tbr, as well as the new TG values I just obtained.
Please let me know your thoughts. Thank you very much. Clear skies. 73!
/sites/default/files/users/user62686/Figure_Tbr.png
/sites/default/files/users/user62686/Figure_Tbv.png
/sites/default/files/users/user62686/Figure_Tvr.png
/sites/default/files/users/user62686/TG%20values-new.png
Aldrin:
Is there any reason why you did not remove the outlier in the Tbv plot? You actually may have two of them. A second will probably appear after removal of the first? You can see them visually separated from the other points.
I still do not like the amount of scatter that you get with these comp data points. Do you know how to run the older single filter image procedure in VPhot/TG using all the available M67 comps as opposed to the new "common" sequence and time series option? Could you share all the images that you used to MZK?
Ken
BTW, how did you embed the .png links into your post? Did you put them into a word/txt document and then copy and paste that into this post?
I'm not so sure about that. In fact, what I did is the old single filter image procedure stated in the VPhot Manual. I'll share with you the images directly that I used for these.
For the .png links, I just simply used the link attachment function in this email and just leave as it was by default (creating the links).
Best regards,
Aldrin