ASI178MM vs ASI432MM

Time

1800
Sunset at 1848

People

Roy, Onkar, Olivia, Azzan, Katie, Connor

Plan

Detector characterization with BigPix (ASI 432MM) & Planetary (ASI 178MM) detectors

Log

1. Follow Start-Up Procedure

   1. Thor instrument rotator home position wont work, 2023-10-02 19:18:15.262     Error     40328764     Command Error: Move using invalid velocity requested     Function Name = Thorlabs::MotionControl::DeviceSupport::CGenericMotor::Home

2. Pointing at Vega

   1. Auxiliary vs normal tracking is different

3. (Align field to north)

Plan for ASI-178 vs ASI-432 matchup.

1. Preliminary Stuff

   1. Put the ASI-178MM and ASI-432MM Sensor Analysis files onto the data computer. These were run by Katie and Ian in the lab and are available here.

   2. We did this. We placed the 4x JSON files (2x for 432 and 2x for 178) in C:\Users\Director\AppData\Roaming\SharpCap\SensorCharacteristics on DC

   3. Put the ASI-432mm on the scope first with the filter wheel (verify filter positions with sharpcap designations – may need to have names re-entered).

      1. We did this as well and verified the filters in SharpCap EFW Setup

   4. Do your best to align the detector to be North-up using the instrument rotator.

      1. We did this as well, we pointed to Alberio and used the Thor Instrument rotator to find that (for this setup) 31deg was the best arrangement to have the field NSEW aligned

   5. IF IT IS STILL LIGHT OUT - take a series of 10 exposures in each filter pointed at clear blue sky. You can follow the guidelines here. Make sure to save as ‘flat’ in sharpcap, and note the detector (432MM).

      1. It aint

2. Field #1:  Phi Cas (mag 5 star in Cassiopeia). Looks like this if you are indeed north-up (top left is phi cas). Note: please use full frame and bin=1 for all observations tonight.

Last minute substitution: due to Phi Cas being at 35 deg directly over Baltimore city, and given clouds are absent to the south, let’s do another field:  18:32:51 +38:50:16

FINDING CHARTS (BOTTOM is the bigpix, top is 178mm, note the FOV differences)

I expect to see this well you will want to have exposures of ~ 1 second when live viewing. Main star is mag ~7, secondary is mag ~8. These are good values to test our setup.

1. Adjust focus to be ideal.

   1. We arrived at 2154.2 with a FWHM in SharpCap as 4.7 on 432 in b1

2. We will use the “Smart Histogram brain” tool to determine optimal gain settings for the field (see below for instructions)  (https://docs.sharpcap.co.uk/4.0/#Smart%20Histogram) 

   1. Note that we needed to restart sharpcap after putting the sensor analysis files in place (see abvoe)

   2. Tools > Histogram (with sensor analysis files in place)

   3. BRAIN appears. Click it.

   4. We want to measure sky background

      1. Check Ignore Image edges/corners (we have vignetting problems)

      2. Click "Measure"

      3. Measure the sky background and note this down (with filter ID). 

   5. Once the background is entered, select

•  

  •  

    • ‘Optimize on dynamic range’

    • Min exposure - 5 s, max exposure 2 m

    • Stacking time 20 m.

    • Read Noise Limit - 50%

    • Save screenshots of the graphs in this google folder, if there is no option to save them as e.g. PDF.

PUT USED VALUES IN PARENTHESES - e.g., rounding to units of 10 or even 50 is fine for actual observations.

1. Once this has been completed, go ahead and observe the field for a few (5-10) exposures in each filter according to the settings above. 

1. END OF NIGHT stuff

2.  

   1. FLATS. Please follow the instructions linked above. Point the telescope at our very own ‘flat’ in the dome, if this was not done earlier on the blue sky.

   2. Darks. Please put the camera in a box or cover with lens cap and take darks using sharpcaps “Capture Dark” option. You can use a 10x average, and otherwise set the exposures and gains to match any combination used above. (There is no need to set or use filters, so if multiple filters used the same gain/exposure they can use the same dark).

NOTE: you can do the darks for the 432MM when you take it off, before putting the 178MM on for its comparison run. This will increase the likelihood of matching temperature, but weight this against the moonrise which will mess up your backgrounds.

Note: If you want, as a bonus, you could observe another field at another declination and fill in a similar table for at least a few filters, for one of the cameras (e.g., the 178). However with moonrise coming shortly after sunset you likely won’t have time.