This is a summary of normal IGRINS use for observers at the McDonald 2.7m telescope

1 IGRINS & Atlas Computer Set Up
2 Taking Flats (~ 1 hour needed)
3 Dome Opening Procedure
4 Start of Night Procedure
5 Setting Up Guiding
- 5.1 On-Slit Guiding
- 5.2 Off-Slit Guiding (for experts only)
6 Using the Data Taking Package
7 !! Taking a 300s SKY Frame each night !!
8 Identifying A0V Stars
9 Changing the Slit Position Angle on the Telescope
10 Closing Procedure
11 Uploading IGRINS Data from the ICC to Box
12 Legacy Notes

IGRINS & Atlas Computer Set Up

On Atlas
1. Log in with IGRINS account.
  1. Ask for username and password if you do not already know it.
2. Open Browser (Firefox has all of these bookmarked).
  1. In the IGRINS bookmarks folder open the following:
    1. SNR Quicklook (http://192.168.2.2/?obsdate=date): For looking at the spectra taken throughout the night to verify observations are reaching the required SNR. Note: The date at the end of the link must be updated to the current observing date from the bookmarked date.
    2. Nightly Observing Record (https://igrins-status.firebaseapp.com/night/date) : Keeps track of all of the IGRINS observations taken in a night. Note: The date at the end of the link must be updated to the current observing date from the bookmarked date.
    3. House Keeping Package: Keeps track of the instrument health--always--monitor to ensure all of IGRINS parameters are within acceptable ranges.
    4. IGRINS Digital Night Log: A google spreadsheet that will auto populate throughout the night per frame taken.
    5. What Target is IGRINS Observing?: Tracks the coordinates put into the TCS, the position angle of the slit, and over-plots the slit onto a 2MASS K-band image of the target. Best if used in parallel with a finder chart, but can be helpful for verifying rotation orientation and pointing.
  2. Open weather related monitoring pages from the McDonald weather links tab in the bookmarks. We recommend the Mt. Lock Live Weather, the McDonald Observatory Clear Sky Chart, and Hodar or National Weather Service for cloud/rain monitoring.
  3. If you want a double check on closing for weather, we recommend keeping the HETSky and HET Night Report Reader pages open. You can monitor when HET closes for weather throughout the night. Note: HET has stricter opening conditions and is on a different peak, keep this in mind.
  4. If you want to see some estimates of live seeing on Mt. Fowlkes (if the LCO telescopes are open and running) check out this link.
3. Open the VNC Viewer to view the IGRINS computer.
  1. Applications → Internet → VNC Viewer
  2. Connect to the IGRINS ICC. Should only require a double click, but you can follow the steps below if needed.
    1. From atlas use the internal ip address 198.168.2.2 but if connecting from outside the network use the external ip address (might need to use McDonald VPN): 198.214.229.87
    2. Port: 5902
    3. Username: admin
    4. Password: [ask someone if you don’t know it. It is the standard IGRINS password]
  3. Input the IGRINS computer password.
On the VNC-viewed IGRINS Computer (ICC):
1. Note: If you are not the first observer in an IGRINS observing block, most of these scripts will already be running. Be sure to check that they are at the beginning of every night. Regardless if IGRINS is on or off the telescope the ICC should always be running the run_icshub.sh script since this enables the House Keeping Package (monitoring the health of IGRINS). Never close the terminal running run_icshub.sh at the end of a night of observing. We include how to run all of the scripts IGRINS requires to function for a night of observing for clarity, even though most of them run on the ICC at all times.
2. Open a terminal window.
  1. > cd ~/igrins_admin
  2. > sh ./run_icshub.sh
    1. The IGRINS Hub should appear--verify that the date of observation is correct.
    2. Click “check Mount”. It should say “Okay.” If “Check Mount” is Failing:
      1. Open a new terminal window.
      2. > cd ~/igrins_admin
      3. sh ./mntrun
      4. Enter the IGRINS computer password.
      5. Click the “Check Mount” button in the IGRINS Hub, which should hopefully return the status to “Okay”.
        If “Fail” again: remote into IGRINS detector computers. If not able to login [add link], check the computers are turned on in the electronics rack. If they are turned on, there is likely an issue with the fiber optic cable--contact observing support.
    3. Click “run HKP” & verify the health of the instrument.
3. Open a new terminal window.
  1. > cd ~/igrins_admin
  2. sh ./run_all_scripts.sh
    1. The terminal for this should take up the entire length of the screen--it runs multiple scripts with outputs that are hard to read otherwise
    2. This script runs multiple scripts that allow for the use of the firebase apps that update throughout the night (see the IGRINS Bookmarks tab on Atlas Firefox)--these improve quality of life greatly but are not strictly required.
4. Open a new terminal window.
  1. > cd ~/igrins_admin
  2. sh ./run_file_transfer_daemon.sh
    1. This script manages the file transfer between the ICC and the IGRINS computer. Do not close the pop-up window!
On Atlas, Launch the TCS. Make sure you are using the '2.7m Cass F/9' mount model.
In the IGRINS Hub click “run TCSProxy”.
1. Verify that the top of the pop-up says “TCSProxy HJST 107””.
2. Verify that the coordinates from TCSProxy match those in the TCS window on Atlas.
  1. If all of the coordinates read as 0’s, then the Colossus computer might have failed. Phone for observing support locally.
In the IGRINS Hub click “run SCP” and “run DTP”.
1. On the SCP (Slit Camera Viewer), click “Single” in the Detector Control (box 13).
  1. Verify that a slit camera image is produced (box 5).
2. On the DTP (Data Taking Package) click “Test Exposure” on the bottom left under the K-Band image box (box 1)
  1. Verify that an image is produced in H- and K-Band
  2. Verify that the TCSProxy coordinates are not all 0’s (that the connection between IGRINS and TCS is good).
    1. If all coordinates read as 0’s, then the Colossus computer might have failed. Phone for observing support locally.
3. If for whatever reason, either of these fail, phone for help!
To enable sounds from the IGRINS observing computer in the observing room:
1. Open a terminal in Atlas (NOT the ICC! Open the terminal on ATLAS!)
2. > cd igrins_tools
3. > cd play_msg
4. > /home/igrins/miniconda3/envs/igos3/bin/python play_msg.py (running the script the enables the notification sounds).
On the Atlas computer open the following:
1. The MONET sky camera (pink “SKY” button pinned to the taskbar).
2. The HJST dome floor camera (pink “HJST” button pinned to the taskbar).
3. The HJST slit camera (pink “SLIT” button pinned to taskbar).
4. The Night Report (enter name info and add report content throughout the night).

Taking Flats (~ 1 hour needed)

Go out in the dome
1. Go to the old control room (Colossus Control Room) and press each of these buttons:
2. Go to the console and press "Reset". You will hear a click as the breaks preventing the telescope from moving are released. There should be no messages on the TCS now.
3. Move the telescope to the Flat position
  1. On the TCS monitor in the dome, click the “Next” menu, click “Flat”, and click “Yes” on the warning message that pops up.
  2. Click “Go Next” at the top of the TCS window.
  3. Push the Autoslew button to move the telescope to the Flat position.
  4. Use the yellow hand paddle to move the upper wind screen all the way down to reveal the full flat screen.
4. If the dome is not in the “Park” position, use the TCS to move the telescope dome to the “Park” position
  1. Using the TCS monitor in the dome, click the “Tools”, click “Park”, and click “Yes” on the warning message that pops up.
5. Set up IGRINS and telescope for taking calibrations
  1. Raise the east platform so you can reach the top of IGRINS
  2. Open the shutter on top of IGRINS is for taking flats
  3. Be sure to secure the window cover arm using the velcro.
    IGRINS window cover handle in the open position.
  4. Lower the east platform back down.
  5. Use the console to open the telescope mirror cover.
6. Turn off all the lights in the dome and cover the TCS monitor in the dome with the blackout fabric.
In the Observing Room:
1. In the DTP on the ICC:
  1. Click the “FLAT-OFF” button below the K-band image plot (box 1).
    1. Click “Yes” on the pop-up that appears (this just fills in the Object Name and Exposure Time in the DTP).
    2. This will fill the Seq Bar with 10 x E frames, change the object name, object type, and set the exposure time (boxes 7, 3, and 6).
  2. If there are 3 flat lamps working you will need 30 second exposures, if all 4 are working then 20 second exposures will do.
  3. Change the exposure time to 30 seconds (box 6; if not already set to that).
  4. Change the Object Name to “FLAT 30s” (box 3; if not already set to that).
  5. Verify that Frametype is “OFF”.
  6. When ready to take the FLAT-OFFs, click the “Start/Resume Sequence” button (box 8).
2. FLAT OFF frames should take about 10 minutes to complete. Computer will say "H finished", "K finished", “Sequence finished” when they are done.
Back to the dome to turn on the Flat lamps for FLAT ON frames
1. Turn on the dome passage lights for safety.
2. Move the rolling stairs from their stowed location to platform east near the telescope
  1. Ensure the location you place the rolling stairs is clear of the telescope and not off the moving platform entirely.
    When the lift raises, if the rollings stairs are placed under the telescope it can damage the instrument or the telescope!
3. Raise the platform using the yellow hand paddle until you will be able to reach the plug for the flat lamps on the side of the telescope
  1. !! Make sure you do not get close enough to bump IGRINS with the raising platform !!
4. Plug the flat lamp power cable into the side of the telescope, see images below
  The lamp power cable is usually laying on the ground of platform east next to the platform console.
  The plug location on the side of the telescope when in Flat or Zenith position.
5. Turn off the dome passage lights.
In the Observing Room:
1. In the DTP on the ICC...
  1. Click the “FLAT-ON” button below the K-band image plot (box 1).
    1. Click “Yes” on the pop-up that appears (this just fills in the Object Name and Exposure time in the DTP).
    2. This will fill the Seq Bar with 10 x E frames, change the object name, object type, and set the exposure time (boxes 7, 3, and 6).
  2. If there are 3 flat lamps working you will need 30 second exposures, if all 4 are working then 20 second exposures will do.
  3. The peak counts per FLAT exposure should be between 6,000 and 12,000 counts (H-band will always be higher than K-band). Inspect the FLATS in DS9 or check the peak flux counts in the SNR quicklook tool (see 1.b. in the Setup above).
  4. Change the exposure time to 30 (or 20) seconds (box 6; if not already set to that).
  5. Change the Object name to “FLAT 30s” (box 3; if not already set to that).
  6. Verify that Frametype is “ON”.
  7. When ready to take the FLAT-ONs, click the “Start/Resume Sequence” button (box 8).
  8. Check the counts using the SNR Quicklook applet (see Step 1b) for the first Flat ON. Counts should be around 10k in H-band (and a little lower in K-band).
    1. If the counts are significantly below 10k, leave a note in the night log for the day crew to inspect the flat lamps and retake the flats with a higher exposure time. Note the correct flats to use in the IGRINS digital log (see Step 1b).
2. FLAT ON frames should take about 10 minutes to complete. Computer will say "H finished", "K finished", and “Sequence finished” when they are done.
3. If you changed the FLAT exposure time in the FLAT ON process, then retake the FLAT OFF exposures with the same exposure time.
4. When the sequence is finished, in the dome turn off flat lamps and return the upper wind screen to its stow position using the hand paddle.
  1. Close the telescope mirror cover on the console so nothing falls on the mirror when moving the upper wind screen.
    The top windscreen should be stowed ~6 inches above where the chain for the windscreen motor becomes hidden (the red box). You can also check to make sure that the windscreen aligns with the slit on the dome ceiling (image on the right).

c. Unplug the flat lamps from the side of the telescope.

d. Stow the ladder on the side of the dome floor (off of the lift platform), out of the way.

f. If you are not going to directly start observing after taking flats, press E-Stop.

Dome Opening Procedure

To startup the telescope follow the dome opening procedure. Be sure to monitor the weather conditions and abide by the dome closing conditions while observing!

For reference during dome opening procedure.

If all prior steps were completed, then the remaining steps are:

Turn off the dome lights and passage lights.
Prop open the doors on both sides of the dome.
Open the Louvers using the Air Controller panel by the east door.
Open the slit by holding down the "Dome Open" button on the console. This will take a few minutes. You will hear a clank when the dome is fully open. Once the slit is open, you can let go of the button.
Press and hold the "Cover Open" button on the console to open the mirror cover. You will hear a sound when it fully opens (note the light indicator no longer works, so listen for the sound). Once it is open, you can let go of the button.
On the TCS monitor in the dome or ATLAS, select Tools → Enable Dome Automation.

Start of Night Procedure

Check and zero the telescope pointing
1. If TCS has not been reset since the prior night of observing, your pointing will be easier to find than if TCS was reset during the day.
2. Follow either of the directions outlined here:
  1. How to zero the telescope pointing in TCS
  2. Telescope Pointing Procedure
3. Note: Since IGRINS has returned to McDonald Observatory in late 2024 the pointing has been difficult to obtain because the zeroes are often far off when TCS is reset. Be prepared to spend up to several hours in the beginning of the night pointing (particularly spiraling around using the paddle in the SCV), especially if you are not an experienced user of McDonald HJST. Our advice to make pointing easier is to pick a star near zenith that has several surrounding bright stars (see example 29 Peg) because if the telescope is very far off in pointing nearby bright stars clustered by dim stars are easier to identify in the slit view camera images than clusters of all dim stars. Remember to take into account the slit rotation when looking at finder charts!
  1. Pointing is often easier after your first night of observing, it will be most difficult for the observer at the very beginning of an IGRINS run when IGRINS has just been placed back onto the telescope--prepare accordingly if you are this observer!
Focus the telescope
1. Use the yellow hand paddle in the observing room to adjust the telescope focus
  The hand paddle is located to the right of the ATLAS computer monitors.
2. Make sure there is a star near the center of the SVC field of view that is bright enough to measure the FWHM of its PSF but not so bright it saturates the detector.
3. It might be useful to set up a spreadsheet/notes to record your focus values vs. star PSF FWHM
4. Select minimum and maximum range of focus values to check (Note: Focus generally falls between 58,000 and 65,000), start at the lowest range (we recommend a few hundred away from the focus used the previous night of observing).
5. Start at the minimum and loop through the following procedure (there is hysteresis in the system so we always step through the same way)
  1. Step up in values of 200
  2. Take a 4 second slit view camera image.
  3. Click the star to measure its FWHM [put in image of the plots we use to measure this from the SCV]
  4. Keep an eye on the shape of the star’s PSF and make sure it looks reasonable [show an example of the tail that can appear when things are out of focus]
  5. Record the focus value and the the FWHM of the star in the SVC image.
  6. Repeat the above steps, filling up your table, until you reach the maximum focus value to check or you are confident you are out of focus.
6. Find the focus value that gives the best FWHM (it might be useful to plot your table in a spreadsheet).
7. Go back to the minimum focus value
8. Slowly in small steps raise your focus value until your reach the value that gave you the best FWHM
9. Take another exposure of your star and double check you get the expected FWHM
10. If you are confident the PSF FWHM is good, you are now in focus!
  An example of a good focus PSF. You can click on the Gaussian-fitting box to toggle between this view and the Gaussian fitting of the PSF that measures the FWHM.

Note: If there are large changes in temperature over the night and/or you notice the stellar PSFs in your SVC images look bad, you might want to refocus.

Setting Up Guiding

On-Slit Guiding

Our guide to on-slit guiding using the SCV GUI can be found here. This guide includes the guiding reset procedures in the event the target falls off of the slit while spectra are being acquired and if the target does not slew to the correct nod position on the slit.

Observers should always be monitoring the target position on the slit during on-slit guiding. Targets centered on the slit during observations produce better quality, higher SNR, reduced 1D spectra!

Before moving the telescope to a new target, make sure that guiding is stopped!

Off-Slit Guiding (for experts only)

In SVC Package window Nodding box, select “Custom (see the advanced pane)”
At the bottom of the SVC Package window, click the “Advanced Pane” checkbox
For Off-slit guiding we generally set “Every” underneath the “Stop Guide” button in the “Detector Control” box to 1.
In the Advanced Pane check the “Use Guide Position” checkbox
Under A-B Guide Box Position in the Advanced Pane…
1. For nodding on slit (ABBA)…
  1. Make sure dA is set to -3.3 and 0.0 for SL and SW
  2. Make sure dB is set to 3.3 and 0.0 for SL and SW
2. For nodding off (ON-OFF) slit with target centered on the slit …
  1. Set dA to 0.0 and 0.0 for SL SW. This will put your target at the center of the slit.
  2. Set dB to how far off you want to nod for the OFF. Make sure your guide star can still be seen. Alternatively you can manually nod to your OFF position using the digital hand paddle in the SVC Package. For example you could nod 300 arcsec North, take an off, then nod 300 arcsec South to go back. When you do this you need to move each time you change nods and take your A and B exposures one at a time.
  3. Click the “Select A-B & Guide Box Position” button.
To set the guide box position…
1. Method 1: Unknown Offset (Target visible but faint) - click and guide. Off-slit guiding when you see the target and the guide star in a slit camera view but don't know the offsets.
  1. Take a single SVC exposure
  2. Place the target on the reference position by clicking the target, and "Go R" button. It should then say “R” under “Current.” Take another exposure. Repeat “Go R” and taking single exposures until your target is as well centered as you can get it on the little circle. This is important because you want to center your target as well as you can on the slit when taking its spectrum. Once you are satisfied the target is well centered, do not take any more exposures.
  3. Click the guide star and then click the button "Sel G".
  4. Make sure the pink box moved on to the guide star. If it is not perfect, repeat clicking the guide star and “Sel G” until you are satisfied the guide box crosshairs are centered on the guide star.
  5. Click "Nod to A”. It should then say “A” under “Current.”
2. Method 2: Known Offset in Slit_length (dSL) and Slit_width (dSW) Off-slit guiding with known offsets in slit length and slit width between a target and a guide star.
  1. IMPORTANT: Make sure in the “Move selected Target” box under “Current” it says A and not R. If it says R or ?, click SVC image near the slit, and then click the “go A” button.
  2. Under A-B & Guide Box position in the Advanced Pane, set dG SL and SW do your desired values.
  3. Click the “Select A-B & Guide Box Position” button.
  4. Take a single SVC exposure
  5. In the SVC image, click your guide star
  6. Under “Guide Box Position” in the Advanced pane, click the button “Go G”
  7. Make sure the guide box is centered on your guide star. If it is not perfect, take another SVC exposure, click the star, and then click the “Go G” button again. Repeat until you are satisfied the guide star is centered in the crosshairs of the guide box.
Take a single exposure. Check that the guide star is roughly centered in the guide box crosshairs. If it is not, click the star and click the button “Go G.”
Under “Device Control” click the button “Guide”. This will start the guiding.
Watch the guiding. Once you are satisfied the guiding is good, you can move over to the Data Taking Package and start your science exposures.
When you are finished taking data on a target, if your next target will use on slit guiding, reset the guiding settings.
1. Uncheck the “Use Guide Position” checkbox
2. Uncheck the “Advanced Pane” checkbox
3. In the nodding box, select “A-B”
4. Check that A and B boxes appear in the correct places over the slit
5. You can probably set “Every” under “Detector Control” back to 2 for on slit guiding

Using the Data Taking Package

The Data Taking Package is used to acquire IGRINS spectra throughout a night of observing. Check out the simple instructions on how to use the DTP here and for a more detailed description of all the button options check out the DTP GUI outline here.

!! Taking a 300s SKY Frame each night !!

The PLP requires a 300s SKY frame for deriving the wavelength solution. If you do not observe a sky frame your wavelength solution will not be as accurate and you will frustrate whoever ends up reducing your data. A sky frame should be observed near the middle of the night if possible.

To take a SKY frame:

Move the telescope to the zenith.
Click SKY at the bottom of the DTP window, next to the other calibration buttons.
Click ‘Start Sequence’ to take one E exposure.
Continue observing after you have the SKY frame.

Identifying A0V Stars

Kyle has written several A0V Star worklists that can be used to identify nearby A0V stars throughout the night. Each worklist has to be uploaded to your TCS user account (only once!) for you to be able to use them throughout the night--they are already uploaded to the IGRINS Team user account! You can download the worklists from here the Wiki or from here on Google Drive.

The worklists are organized by magnitude, so if you notice there are not many available A0V stars nearby your target try using a fainter magnitude worklist!

To use a worklist, in the TCS go to Next->Worklists and click one of the uploaded worklists (called A0V_min_Vmag_X). Two new panels will appear for TCS, one with a list of all of the names of the star in the worklist with other info included and a map of where all of the stars in the worklist fall on sky (appear as blue circles on the map). The current telescope pointing location on sky is marked with a red circle with a plus through it on the map. You should pick an A0V star nearby to your target with as close an airmass as possible to the target. To see the airmass, click one of the circles on the map and the airmass will appear in the “Next Airmass” box on the bottom middle of the TCS. We try for airmass matches within 0.1 of the mean airmass of the target if possible (this provides the best telluric correction).

Be sure to verify that the A0V star is a single star using SIMBAD and check that nearby stars will not also fall onto the slit for your current PA. You can do this either using Kyle’s IGRINS Observing Planner tool or by looking at the 2MASS image in the “What Target is IGRINS Observing?” GUI which will update once you click one of the circles in the TCS map. Remember that IGRINS on HJST has better spatial resolution than 2MASS so if there is a star close by but doesnt quite fall on the slit in the 2MASS image, you will probably be okay but always verify with a slit camera image after slewing to a standard. If you notice multiple stars on slit for an A0V observation you must pick another A0V otherwise the data reduction of the target will be incorrect!

Finally, calculate the exposure time using the K-band magnitude in SIMBAD required to reach at least the desired SNR of your target observation(s) using the equation found in the SNR Estimates and Guidelines at McDonald. If your A0V star does not meet the required SNR for your observations, even if your target reaches the required SNR, your final reduced data will not reach your required SNR.

Once your standard is observed, it is good practice to note what standard goes with what target in the IGRINS Digital Night Log in the comments field for the target and in your personal notes for the night. This is helpful when crafting recipe files for reductions to ensure the correct standard is paired with the correct target, especially in cases where multiple targets will share the same standard.

Changing the Slit Position Angle on the Telescope

Move the telescope to Zenith
1. Using the TCS select Next → Zenith and click yes on all of the pop-up windows.
2. Click “Go Next” at the top of the TCS window.
Slew the telescope to Zenith by holding down the Autoslew botton on the dome floor console.
NEW METHOD FOR NOW: Find the pipe titled “IGRINS ROTATOR TOOL” which might be behind and place it on the East Platform floor in a way to ensure it won’t roll off. You will use it as a lever to turn the instrument.
Ensure the rolling ladder for plugging in the flat lamps is not under the telescope.
Use the yellow hand paddle to raise platform east until you can comfortably reach the mount that connects IGRINS to the telescope.
1. Not so high that IGRINS or the electronics rack will hit the platform floor!
OLD METHOD IGNORE FOR NOW: Get the wheel attachment and wrench from the red tool box on the opposite side of platform east (see image in step 7 below; found near the ladder that brings you to the second floor in the dome) or kept on the dome console.
There are four screws on the IGRINS rotator plate that need to be loosened.
1. 3 should have star-like handles (boxed in pink in the image below) you can manually loosen (unless a Darrin has been applied recently… then good luck)
2. The last screw is a large hex screw (on the corner of the rotator plate near the calibration unit; boxed in orange in the image below) that needs to be unscrewed using the large hex wrench (pointed to with the red arrow in the image below) kept on the top of the dome control console.
  Showing the shape of the standard star handled screws (pink box), the special mount locking screw (orange box), and the hex wrench used to unlock the special mount lock screw (red arrow) on the rotator mount.
OLD METHOD IGNORE FOR NOW: Once all of the screws on the rotator plate are loosened, attach the wheel attachment to the rotator peg on the rotator plate.
1. This can be a little fussy to attach because the wheel and peg have interlocking parts, so a headlamp or flashlight can be helpful for getting the right orientation of the wheel.
2. You’ll know the wheel is in position when it is near flush against the rotator peg.
  The rotator peg (boxed in orange) with the wheel attachment (boxed in red) attached.
OLD METHOD IGNORE FOR NOW:Turn the wheel to rotate IGRINS in the appropriate direction.
1. This requires some elbow grease!
2. If you have difficulty moving IGRINS with the wheel alone, attempt applying some pressure on the edges of the electronics rack to loosen the rotator plate.
3. DO NOT PUSH ON THE CRYOSTAT
NEW METHOD FOR NOW: Close the IGRINS shutter to ensure no dust or debris falls in when rotating with the pipe.
NEW METHOD FOR NOW: Place the IGRINS ROTATOR TOOL pipe between holes in the black bracket that mounts IGRINS to the telescope in such a way that you can then use the pipe as a lever to turn the instrument on the backend of the telescope. Place the pipe in the mounting bracket from on the side of IGRINS opposite of fromthe cold head and readout electronics to avoid accidently damaging those components and to be on the same side as the encoder. There are a couple ways you could place the pipe, but the location pictured below keeps the pipe angled below the back end of the telescope.
NEW METHOD FOR NOW: Push on the end of the pipe using it as lever to rotate the instrument to your desired position angle. This might require some strength. Be very careful not to run into hoses, wires, or the backend of the telescope. You might need to readjust the placement of the pipe Check the encoder to ensure you rotate IGRINS to the desired position angle.
Encoder settings for different position angles can be found here.
1. Once you think you are close to your desired rotation position check the value on the encoder and adjust as needed.
Once you reach the desired position
1. OLD METHOD IGNORE FOR NOW:Remove the wheel and return it to the tool box. NEW METHOD FOR NOW: Slowly remove the pipe and place it carefully on the floor of the East Platform. DO NOT FORGET: Reopen the IGRINS shutter.
2. Screw in the 3 star-handled screws on the rotator plate. They should be tight!
3. Use the wrench to tighten the last special screw and return the wrench to it’s found location.
Verify that the cooling cables are NOT UNDER THE PLATFORM before using the hand paddle on the dome floor console to lower platform east.
1. This may require that you lower the platform a little, jump off, adjust the cables, and continue lowering the platform (repeat as needed).
NEW METHOD FOR NOW: Return the IGRINS ROTATOR TOOL pipe to where you originally found it.
In the control room:
1. In the ICC on the SCV GUI change the the rotator value (box 10) and on the TCSProxy change the rotator value.
2. Resume observing!

Note: the on sky drift for guiding while observing is always higher when IGRINS is not in PA = 90 deg, so you may have to adjust the frequency that the guiding offsets are sent to the TCS (box 15 in the SCV GUI).

Return IGRINS to the stow position at PA = 90 deg at the end of the observing night.

19E0C197-71F9-4330-8202-B3135DFD8BC7_1_201_a-20241213-174217.jpeg

The stow position is marked on the rotator plate and the telescope and will align (see red box) when PA = 90 deg on the encoder (orange box).

Closing Procedure

Some of these things can be done in any order, and some things should be done in an explicit order. When the order doesn’t matter, the text is in teal.

Observing Cookbook at McDonald HJST 2.7m