A Few Recent Images

A few recent test images with new filters…
Images converted from 16 bit FITS to low res Jpgs

M57: www.flickr.com/photos/9885064@N05/4546300588/in/photostream/
M3: www.flickr.com/photos/9885064@N05/4546300254/in/photostream/
Spiral Galaxy NGC 4319 & Quasar Mrk 205:
www.flickr.com/photos/9885064@N05/4546303600/in/photostream/
www.flickr.com/photos/9885064@N05/4546300918/in/photostream/
M27: www.flickr.com/photos/9885064@N05/4546303224/in/photostream/
Comet C/2009 K5 McNaught: www.flickr.com/photos/9885064@N05/4546302686/in/photostream/


Clear skies
Mike

Hey Mike, I really like the NGC 4319 & Mrk 205 shot, it's a refreshing change from the usual targets, that's a really deep field, it's nice to peer out that far

Keith.

Some great shots there Mike, keep up the good work.

Hi Mike,

I've rarely seen images taken on these boards using the Cousins UBVRI filters. I see you've taken some very good shots using the BVR filters.
Using these filters is an extremely useful tool to determine the colour. Have you explored any two images yet through different filters and then measuring the apparent magnitude?
In particular, to determine the colour index and approximate temperatures of the field stars. I know you are using MIRA PRO which is a powerful tool for processing images.
I find that Maxim DL is rather limited in this respect.

I took a lot of images about 2 years ago of different galaxies in BVR in particular. Interestingly enough, when you look at the each image in different filters you can see some of the individual stars have either enhanced stellar appearance or a decreased stellar appearance. Its a good indication of the temperature differences between the stars. I have found that the transmission of the Cousins filters certainly reduces the amount of light through them, depending on the filter used. I found I had to increase the exposure time to obtain a much higher magnitude threshold.

I am now about to experiment with the Sloan Digital Sky Survey ugriz filters. Actually, I only got the " g " and the " i ", as these were appropriate for the blue and red bands in some new experiments I will be trying out soon. Although the spectral response is wide , the transmission on both filters is huge at about >95%. This has a significant advantage when imaging faint stars. The only problem I foresee is that I haven't figured out calibrating the Sloan filters to an acceptable photometric magnitude. When using the Cousins filters you can use Landolt stars for calibration. Landolt star don't have Sloan calibration. Unfortunately, there are very few observatories using the the Sloan filters. I haven't checked yet if MIRA accommodates this processing.

I'll be interested on how you are getting on.

Eamonn A

www.kingslandobservatory.com

Eamonn

Fermilab appear to host a Landolt-type table of standard stars for u'g'r'i'z' calibration.

www-star.fnal.gov/ugriz/tab08.dat
www-star.fnal.gov/ugriz/index.html

Is that the sort of thing you're after?

I have to say - until you posted I'd never heard of this filter system - thanks for that.

Mark

Thanks Guys
This target was a challenge for me and my astronomical equipment but I am glad with the results, it’s surprising what any of us here can do with modest gear these days from a backyard. Hi Eamonn, yes, I have been using Mira Pro in working with image sets, astromertic calibration and basic aperture Photometry etc etc. It’s really excellent software; although I am no expert by any means I am learning by doing.
Your right about the light transmission levels using the UBVRI filters, I find that I needed to increase the exposure time to compensate, it takes more effort to get right and it brings it own challenges but the rewards I think outweigh the option of not using filters.

If any IFAS members with larger telescope aperture and CCD could image NGC & Mrk 205 whether filtered or not and post here for comparison that would be great. The alignment of this Quasar and galaxy is a real odd couple indeed and a good deep sky challenge.

Clear skies
Mike