Hello! I’ve got my dark frames working. (See my previous posts).
I’d like help figuring out the source of error in I filter for V0645 AUR. I updated the comps from what I used several years ago, but it does no matter which stars I pick as check and comps from the 4 listed in my 18 min FOV, the errors are about 0.4 to 0.8 mags - too high to report. I am unsure how to proceed with identifying the source of such high mag error. I’ve uploaded both the raw and calibrated frames. Thank you.
Hi Mike
I see that your current B and V agree with your old data. Your I data is about 4 magnitudes brighter these days. Did your I filter fall out?
I was able to solve the images with PinPoint and I uploaded them to VPHOT to see what I can see for comps. They are stuck behind my own backlog, so it will be awhile.
You are right! The same change with RR Cet and SZ HYA I filter mags. The system is set up at Starfront in Texas. I’ll ask them to take the SBIG ST402 off and visually check the I filter. I hope nothing has happened to it sine these filters are not made any longer.
Thank you for checking this. I had not thought of going back 5 years to my last I images to check - I’m still in the equipment shake out phase for the new installation.
Thanks! I’ve asked AAVSO to delete all my I-filter submissions for the last month till I get this figured out.
It looks like it is my use of the I transform rather than the physical filter! I re-ran the reduction without transform, and I get your value near 9.5 with good error bar. When I applied the I transform, I get a magnitude closer to 6 rather than 9 with large error.
So, it is a problem with the transform rather than the physical filter.
What a relief! Now I don’t have to worry about a dislodged filter.
I had used GD 279 standard field for the transform, and I obviously made a major error in I filter. I recently obtained M67 images to update the transforms, which I used in the past. I’ll update the transforms and redo V0645 AUR to see what I get with the updated transformed result.
Again, thank you for your help. Best regards.
Success! I redid my transforms with M67. Now I get what I’m supposed to get with an error of 0.01 mag in I.
Bad I-filtered images deleted as well.
Thank you for your help and best regards.
Great! Glad you found it.
Are your B and V filters OK? The old glass B and V filters tended to frost, blurring the stars on the image. I just cleaned one up with toothpaste and gentle rubbing. An idea that I found here on the old forums.
I ruined it because I had to re-learn the Gentle part while experimenting with cleaning it and it may not be flat over the whole surface anymore. I measured it and the passband was still good. If I had tried the toothpaste first, I may have been able to reuse/donate it.
Today’s newer, interference-style filters are much more efficient and don’t frost.
