GRAS FITS

[johnb]

Hi

I have recently been looking at the GRAS System (rent a scope) and been able to get some semi decent shots, when using the system for each exposure you get a Jpeg pic which is fine and a FITS file which when you try and stack in DSS seems to do nothing almost like the file has no data ie DSS will detect 2 or 3 stars. Im sure the data is in the file but how to get it out ? - anyone use GRAS and DSS ?

Regards

John B

[Paxo]

Which scope were you using John, by getting a jpg I'm assuming it was a One Shot Colour?

Have you downloaded the calibration files as well (darks, bias flats), that will make a massive difference.

Steve..

[johnb]

Steve

Yes the 1 shot color option on GRAS 3 I have 10 300 sec image files and 3 x 300 sec darks, i will see if I can get Bias and Flats as well and try again

In dss are there any optiosn i should select for FITS files ?

Regards

John B

[johnb]

Sorry another question, even without the Flats and Bias files would the registration process in DSS say register a few stars per image ?

John B

[Paxo]

John,

Apologies if you have already done this. Take a look in the options section on DSS, you will need to look at the settings/Fits file tab and ensure you have all the right settings in there, ie click on the monochrome fits from colour, I'm not sure which camera matrix you need. You can alter the source brightness here if necessary.

The next thing to ensure is that when you register the checked pictures, goto the advanced tab on the window that appears and lower the star detection threshold to as low as possible.

My experience of the GRAS system is that they give excellent images but require good calibration files. They are using larger chips so flats are very important, and can be quite noisy so good bias and darks too.

Good luck, let us know how you get on.

Steve

[Paxo]

Sorry another question, even without the Flats and Bias files would the registration process in DSS say register a few stars per image ?

John B

It would but calibrating the images will make life a lot easier, particularly with the flats, that will "equalise" the illumination accross the field and allow more stars to be detected and used.

One thing to bear in mind, the system that creates the jpg calibrates and stretches the image using a digital development filter.

Steve

[johnb]

Thanks for that, yes all that made a difference, I think its now all down to which Camera Matrix, first go attached which gives me a lot more than before.

Thanks for you help

John B

[Paxo]

Looks good John, let us know how you get on.

Steve