David's Astronomy Pages
CCD Imaging

Bullet CCD Camera
Bullet First Images
Bullet Initial Teething Problems
Bullet Experience & Comments
Bullet Accessories
Bullet Books
Bullet UT/BST Times
Bullet Imaging Practice

See also
- CCD Imaging Performance 2001-09 to 2002-01 describing my first 4 months of CCD Imaging.  
- Imaging Sessions for latest CCD Images look at my page. 
- Scripting for information about my Telescope/CCD Image Scripting 

CCD Camera

My CCD Camera is a ST-7E manufactured by SBIG (USA) and supplied via BCF in London. (picture of ST-7)

The ST-7 camera uses the KAF-400E CCD chip (765 x 510 pixels, with pixel dimension of 9 x 9 microns).  A non-ABG camera was ordered, but it is currently suspected that the camera supplied is actually an ABG camera (details)

Camera control is performed via CCDSoft v5 program written by Software Bisque. The software was supplied with the camera.

[ Technical specification of ST-7 camera (at SBIG Website) ]
[ Technical specification of CCDSoft v5 program (at Software Bisque Website) ]

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First Images

Some of the first pictures taken with my ST7 camera are shown below. They don't really to justice to the capabilities of the ST7 camera, but they show my first achievements.  For more recent images look at my Imaging Sessions page.

First night - stellar imaging
(images 2001-09-25)

Double-Double in Lyra
2001-09-25,  23:16h UT (#2014)
8 secs exposure
Due to poor focusing and/or poor seeing the binary components of each of the 2 main stars could not be resolved. Previously I've been able to resolve the binary components
(See previous Visual View through eyepiece 1996). Subsequently,  deconvolution was used to process the image and just resolve the pair of close binaries (notes 2001-09-25)  
Image Second night - lunar imaging
(images 2001-09-29)

2001-09-29,  21:36h UT
0.5 secs exposure (#4030)

Due to high brightness of the near full 
moon, the aperture of telescope was stopped down to less than 2 inch. This limited the resolution achieved.

Image Third night - lunar imaging
(images 2001-10-03)

2001-10-03, 23:01h UT
0.2 sec  exposure (#5037)

Image Fourth night - deep sky imaging
NGC 7331, Spiral galaxy in Deer Lick Group

2001-10-11, 20:49h UT
60 sec  exposure (#6002) Stars imaged down to at least Mag +14.8 in this 60 second exposure.  
(previously Mag +12 was my visual limiting magnitude)
Longer exposures started to show trailing/Pec wobble
(I'm waiting on a replacement RC Adapter from SBIG to enable PEC training & autoguiding)
Image Image Image Fifth night - low resolution planetary imaging,
Jupiter & Saturn

0.05 & 0.1 sec  exposures, 
Unsharp masked  (#8080 & 8043)

Saturn - various exposures, various unsharp-mask processing    

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Initial Teething Problems

Initial Teething problems and solutions are listed below


Solution :  Telescope / Server Settings modified in the TheSky to allow remote connections/allow focus control   (solution originally provided to me by Software Bisque technical support )

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Experience and comments using ST-7

CCDSoft appears to be fully capable for acquiring CCD images using the ST-7.

Some bugs noticed in 5.00.041
a) Problem : Offset time field on the FITS Modifier form will not accept '-1'. Error given as soon as '-' is entered. Workaround : Enter '1' first, then left arrow and then enter '-'

Autosave/Image numbering
I use the Autosave facility in CCDSoft, with an image numbering system with format, sssssnnn, where sssss records the imaging session number and nnn records the consecutive images taken during the session. eg 00006001 is the 1st image taken during the 6th observing session.

At the start of each session I set the Autosave Starting number to  sssss001 (eg 6001) and the autosave folder to ../Ccd Imaging/New/yyyy-mm-dd/  where yyyy-mm-dd is the observing date.

Mechanical Connection to Scope
The standard connection provided with ST-7 is a 1.1/4" nose piece. When connected into a 1.1/4" eyepiece holder with a single thumb-screw, the ST-7 is in danger of falling out and/or slop.

I've now bought a #62 T-Adapter, which allows the ST-7 to be screwed securely to a T-Thread. In practice I connect the ST-7 and T-Adapter to a Thread to 2" nose adapter, which I insert into a JMI-NGF-S focusser and tighten with a pair of thumb-screws.

An assessment of CCD Imaging Performance from my first 4 months use of the camera is documented. (CCD Imaging Performance 2001-09 to 2002-01)


CCD Operating Temperature

Graph showing CCD Operating Temperatures used in SBIG through year.
(note SBIG 7e camera cools up o ~ 30 deg below ambient)


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The principal accessories associated with the CCD camera are
- 3D Counter Weight system 
- JMI NGF-S focusser controlled via CCDSoft and TheSky

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Books that I own and have read on the subject are as follows

I've also borrowed and read the following book 


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UT/BST Times

BST times are 1 hour greater than UT times

To analyse FITS images for a minor planet using CCDSoft/TheSky, times (TIME-OBS, DATE-OBS) must be in UT times.

CCDSoft's | Research | Analyse Folder of Images | FITS modifier | can be used to correct BST times to UT times.    Use Offset Time (hours) of -1 
(Need to be careful to apply change only once)

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Imaging / Analysis Practice

Commencement of CCD Session
1 Create Folder Structure for storing New Images
(performed using a script, which creates 
../new/yyyy-mm-dd S000xx and
../analysis/yyyy-mm-dd S000xx folders (plus subfolders)
where yyyy-mm-dd is the current date and S000xx is the session number.
2 Turn on CCD, connect to CCD and commence temperature regulation using CCDSoft
3 Point CCDSoft's autosave folder to ../new/yyyy-mm-dd S000xx (ensure Autosave is on)
Set 'Starting number' to xx001
Post Session
1 If computer times are in BST then use CCDSoft's FITS Header|Alter Time Keyword to convert BST times to UT times (offset hours = -1)
2 Use own AstroImage Program to 
a) CleanUp filenames (removes the name suffixes, added by CCDSoft during imaging)
b) Create FITS summary.dat  listing (list of images, times, exposure length and type, image size/binning, target objects etc)
3 Copy raw images from ../new folder to ../_raw folder 
a) CleanUp filenames (removes the name suffixes, added by CCDSoft during imaging)
b) Create FITS summary.dat  listing (list of images, times, exposure length and type, image size/binning, target objects etc)
4 Open FITS Summary Template (Excel)
Import FITS summary.dat  file into Excel
Save as 000xx_Fits_Summary.xls
Check/adjust Object names and Bin/Exposure Group details. 
Run excel macro ColourCodeSheetSave spreadsheet
5 If desired, use CCD Imaging Scripts to Analyse Raw Folder  (to record pointing accuracy/FWHM etc)
6 Run excel macro Group_Raw_Fits. This moves raw images into appropriate subfolders for reduction.
7 Review & re-file Flat/Dark Files as required
8 Use CCDSoft's Image Reduction to reduce each set of raw images.  Output reduced files to .../_reduced folder
9 If desired, use CCD Imaging Scripts to Analyse Reduced Folder  (to record pointing accuracy/FWHM etc)
10 Run excel macro Group_Reduced_Fits. This moves reduced images into appropriate subfolders for each object/bin/exposure set.

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