GRB Hunting: A Procedure


 

Step Step Description Step Time in Min Step Notes Time sum
1 Join the AAVSO GRB discussion group. (done once) aavso-grb-list@mailman.McMaster.CA This discussion group provides notification of the burst, coordinates, and error box data.  You may also receive this information on a pager.  Time: Done Once.   GCN notices provide RA/DEC and error box information among other things.  
2 Check Polar Alignment 5 Set using Polar alignment scope and tracking feature of SBIG ST-9 to provide good imagery 5
3 Turn on drive and setting circle computer 0   5
4 Set Digital Setting Circles 6   11
5 Enter Burst Coordinates 1   12
6 Find Field 1   13
7 Set Focus for camera 10 Uses IFocus occular plus fine tuning.  Use clear filter in filter drawer 23
8 Take Field locator image 2 this is a 30 second exposure 25
9 Locate Camera field 5 Due to inacuracies in the setting circles, the located field may be up to one half degree away from the burst center.  This step uses TheSky image-link to locate the camera center of view.  TheSky provides offset information in the form of position angle and distance in degrees from the center of the camera field to the center of the burst field. 30
10 Compute RA/DEC offset 2 This procedure converts the polar angle and displacement from the previous step into a delta RA and DEC number of degrees which can be fed into the telescope controls. 32
11 Apply delta RA and DEC movements to scope 4 Adjustments are made using the slow motion controls for the appropriate number of seconds in each direction.  In general it takes one second to move one arc-minute in declination, and  0.65 seconds to move one arc-minute in RA. 36
12 Take Deep unfiltered image 21 20 minute deep field single exposure.  guidance assisted by ST-9 tracking capability 57
13 Begin Deep Field JC Red image 31 30 minute exposure with Johnson-Cousins Red filter.  Re-focus is not needed because clear glass filter was used during focus step. --
14 Get NOFS image of error circle (this step done in parallel with step 12. 0 Image is available now, so times are no longer a factor.  This procedure uses the pixel generator at www.nofs.navy.mil.   The image size is the size of the error circle diameter in width and hieght. 57
15 Publish error circle and deep frame on www.highenergyastro.homestead.com 5   62
16 Notify AAVSO GRB group that image has been taken. 1 .The intent of this step is to put any available person to work looking for the transient. 63
17 Compare NOFS and unfiltered Deep Field image from camera   Depending on the number of stars in the image, this can take from 15 minutes to one hour --
18 If transient not found proceed to step.R0      
19 Possible Transient found:  Perform image link using deep image using TheSky.  Read out the RA and DEC from TheSky directly. 3    
20 Publish RA/DEC of transient from unfiltered image on AAVSO GRB e-mail channel.  Go to step R5 1    
R0 This step begins when the JC Red 30 minute image is complete.      
R1 Deep Red image is saved to disk, and V filter is installed.  The camera is set to take a 50 minute exposure 50 V exposure begins.  Time has passed, transient is less bright, and the camera is not as sensitive to the V band.  Again, ST-9 tracking automates this process.  
R2 Deep Red image is compared to NOFS image as in step 17.  If transient not found, proceed to step V0.      
R3 Possible Transient found:  Perform image link using deep image using TheSky.  Read out the RA and DEC from TheSky directly.      
R4 Publish RA/DEC of transient from unfiltered image on AAVSO GRB e-mail channel.      
R5 Deep Red image is published on www.highenergyastro.homestead.com      
R6 Notify GRB AAVSO list of existence of Red mage      
V0 Repeat R0 thru R6 for V image   During this step, theB image taking is begun.  This exposure should run for at least 2 hours here to make up for the lack of sensitivity of the camera, and the continued fading of the transient.  
B0 Repeat R0 thru R6 for B image   Shut down telescope system  
  end of procedure