APT + Stellarium Imaging Workflow

I came across an excellent video last week by Matt's Astrophotograpy. Matt's setup and choices for software are much like mine but his experience is vastly greater so I took a lot of notes.

I'm going to post those notes here and alter them as I do more imaging.

Software

Please consult each software's documentation to determine how it is to be configured.

Imaging Control: Astro Photography Tool

Once upon a time I used ImagesPlus camera control, then moved to BYEOS when I switched to a DSLR. My first impression of APT was that it was a mare's nest of capabilities and was too tangled to tame. I tried to like SGP, but the way it functioned seemed counter intuitive. I found NINA interesting but had to give it up when I found it didn't support my SBIG CCD or the QSI I was hoping to buy. Maybe by the time I buy that QSI it will be supported. So I sat down and started learning APT!

Be sure to install version 3.84 or later so you get ASTAP support (see next section).

Plate Solving:

I think you really only need to install ASTAP and its G17 star database. ASTAP seems superior for both near and blind solving compared to the old standards, PS2 and ASPS. And please don't tell me about AstroTortilla. Not to diminish the role it had in bringing plate solving to the masses, I always found it to be slow and unreliable.

Guiding: PHD2

Obviously.

Planetarium: Stellarium

This is a personal preference thing. I like Stellarium; it's pretty and it does what I need. This workflow will make use of Stellarium.

You may want to install version 20.1 instead of 20.2, as the latter requires you to manually connect to the mount.

Stellarium tip: The config.ini file lets you configure Stellarium's defaults. Here are two examples...

Turn off full screen mode, look in the [video] block, and set fullscreen = false

Turn off daytime sky brightness, look in the [landscape] block and set flag_atmosphere = false.

Slewing/Parking/PEC:

Slewing in RA is needed for Polemaster, which will want you to slew your mount several times. This can be done conveniently from within an ASCOM control panel or by using a hand control.

If you would rather slew entirely from within APT, do this:

Start with the mount at counterweight down (CWD) orientation and the RA axis pointed at Polaris. Connect APT to the mount. Copy the values of current RA & Dec to the GoTo fields. To do the requested rotation, usually just subtract one hour from the RA and click the GoTo button. (If the stars turn in the opposite sense of the PoleMaster display arrow, add instead of subtract.) Repeat for the second rotation.

To return to the start orientation, undo the RA changes in one step. DO NOT use the APT park button!

Setup & Initializing

Assemble

Start by assembling the components of your imaging system. This includes making all the data and power cable connections.

If your system is portable, this means rough-aligning your mount to north and balancing it for imaging.

When ready, power it all up: Laptop, Gemini II, imaging camera, dew heaters.

Make the data connection to your laptop. (In my case the data connection must be made after power-up because it could damage the SBIG camera if made too soon.)

Start APT and optional Camera Cooling

Steps marked with an asterisk are required even if not using the cooling aid.

*Launch APT
*APT/Camera / Connect
APT/Camera /Cooling Aid. Check settings and start.
*APT: Tools / ATP Settings / Main. Set image destination folder (optional)

Polar Align

(I use a PoleMaster for polar aligning. I agree with Matt 100%: PoleMaster is the way to do polar alignment.)

 

APT/Gear: Connect Scope (This launches an instance of the GeminiTelescope ASCOM driver.)

Attach PoleMaster to mount, connect USB
Launch PoleMaster software, and connect

Perform slews using one of these methods

ASCOM controller

1. Find the Gemini ASCOM driver icon in the Windows tray area. Right click and choose Show Hand Controller
2. Confirm Speed is "S" and that PEC is checked.
3. Use the hand control RA buttons to perform slews
4. When finished use the tray icon menu to close the hand controller. DO NOT minimize it!

APT

Use the add/subtract RA method described earlier

Disconnect and Remove PoleMaster

Sync

Launch Stellarium

Stellarium: If using version 20.2, manually connect the mount (use the telescope control plugin)

Stellarium: left click a suitable sync star, then use CTRL-1 to go to it

APT/Gear: Open Pointcraft

APT/Camera. Verify that exposure time is appropriate (I use 10s with my ccd and L filter)

APT: Shoot
APT/Pointcraft: "<< Scope Pos" to populate approx. position fields
APT/Pointcraft: Solve
APT/Pointcraft: (assuming solve is successful) Sync
Stellarium: Should now show true position of scope. Use CTRL-1 to center star in FOV
APT: Shoot new image to confirm star is now reasonably centered. If it is not, use Pointcraft Aim as described later and then Sync again

Focus

Please refer to APT documentation to learn how to best use the focus aids. I use a Bahtinov mask whenever possible.

APT/Gear/Filter Wheel/Go To Filter: Select filter to focus
APT/Camera/Bulb Seconds: Set appropriate exposure time

Attach Bahtinov mask
Shoot single images or use Live View. If Live View is used, possibly disable Live View Automation (APT:Tools/APT Settings/Main/Live View Automation) to prevent binning
APT/Tools/Bahtinov Aid: Make sure focal length, aperture, and pixel size are correct; turn on Cross mode

Drag Aid window so that focus star is at crosshairs

Recalc as needed if not in Live View mode
Adjust focus until satisfied with focus
Close Bahtinov aid
Remove Bahtinov mask!

Acquire

Obtain and Compose Target

Obtain a Target Object

    Find target in Stellarium, CTRL-1 to it
    APT Pointcraft:  <<Scope Pos
    APT Shoot image
    APT Pointcraft Solve
    APT Pointcraft Aim, click on image to refine center if desired
    APT Pointcraft GoTo++
    When completed you are good to go.

   
Go To Specified Coordinates

    APT Gear Enter coordinates into Center FOV boxes
    APT Pointcraft GoTo++
    When completed you are good to go.

Resume an Old Session

    Find target in Stellarium, CTRL-1 to it
    Open image from previous session
    APT Pointcraft Solve
    APT Pointcraft << Solved
    APT Pointcraft GoTo++
    When completed you are good to go.

Autoguiding

Launch PHD2
Toolbar Connect Icon or simply CTRL-C, connect guide camera and mount
Main Menu/Tools/auto-select star or simply ALT-S
Click SHIFT-toolbar Guide button to calibrate
Let PHD settle

APT/Gear/Guide to connect to PHD2 and configure optional dithering

Acquisition

APT/Camera Select Imaging Plan

APT/Camera Start

Shutdown

APT/Camera/Warming Aid: Warm the camera slowly (optional)

APT/Gear/SHIFT-Guide to disconnect from PHD2

PHD2/Toolbar/Stop button

PHD2/Toolbar/Connections disconnect all

Close PHD2

Find the Gemini ASCOM driver icon in the Windows tray area. Right click and choose Show Hand Controller

ASCOM Hand Control/Park (optional)

APT/Gear/Disconnect Scope

Tray ASCOM icon/Right click, Exit

When warming is complete, APT/Camera/Disconnect

close APT

close Stellarium

Turn off Laptop

Turn off Gemini II

Disconnect USB cables from any devices that may be harmed (Applies to my SBIG ST-8300M)

Disconnect all from power supply

2020 Nebraska Star Party: What Might Have Been

Fans of NSP know it was cancelled for 2020 due to the pandemic. The cancellation may have seemed a bit premature when it was announced on June 12, but to me it was clearly the right thing to do. During the last month the virus has been spreading almost unchecked in some parts of the country. Nebraska itself has seen a mild rebound in the number of positive tests, but not nearly as bad as what is happening elsewhere. Possibly the good people of Nebraska have more sense than those in a few other states and they're not afraid of masks?

The 2019 NSP was a real dud with only one decent night of the five I was there. Mostly it was clouds and rain. There was hope that 2020 would be better. Then came the virus.

What follows is a night by night summary of what the 2020 NSP sky would have been, based on satellite cloud images, North Platte radar, and observations at Valentine. I don't use cloud observations from Valentine because I don't trust their accuracy. (Valentine will sometimes report clear skies when there is high overcast; go to the bottom of this entry to see an example.) I don't doubt some people are staging a private NSP and can provide better estimates, but until they report I'll depend on my estimates.

Please note that all times are approximate. The time of total darkness each night is now five hours six minutes, extending from about 11:17 P.M. to 4:23 A.M. I'll take this as five hours and rate each evening on a five-star basis; one star awarded per hour of possible imaging. A perfect night would look like (⭐⭐⭐⭐⭐). Because I usually arrive on Sunday and depart Friday morning I'm only going to report on five evenings. How many stars will NSP 2020 earn of the possible 25?

Sunday, July 19 (No Stars)

Daytime: High 87° with dew point around 61° most of the day.

Overnight was cloudy from dusk to about 4:15 A.M. with thunderstorms and rain around 11 P.M. and again at about 12:15.

Monday, July 20 (⭐⭐⭐)

Daytime: High 88° with dew point again around 61° most of the day. Thunderstorms with rain from about 8 until 9 P.M.

Overnight: Overcast until about 12:30 A.M., then clearing with occasional clouds until about 4 AM. About three hours of imaging were possible.

Tuesday, July 21 (No Stars)

Daytime: High 84° with dew point around 59° or 60° most of the day.

Overnight: Blowoff from thunderstorms in southeastern Wyoming spread overhead between 9 and 10 PM. Clearing began around 4:30 A.M. No precipitation was indicated by radar.

Wednesday, July 22 (⭐⭐)

Daytime: High 92° with a 69° dew point (heat index a very sticky 97°). At 9 P.M. (20m before sunset), it's 83° with dew point temperature 69°, winds are 14mph, and cloud cover is about 50%.

Overnight: A poor quality night, with broken high clouds most of the hours of darkness. Occasional wind gusts around 21mph, and heavy dew from dew point temperatures between 71° and 69°. "Clearer" periods from 11:30 P.M. to 1 A.M. and 2:00 to 3:00. Probably some light frames could be gathered during these short holes? If not, then it's a zero stars night.

Thursday, July 23 (No Stars)

Daytime: An even more unpleasant day (96° with a 67° dew point at 4 P.M., heat index 100°), but without the relief of the Wednesday air-conditioned high school.

Overnight: Persistent scattered clouds until a little past midnight, then cirrus from a thunderstorm passing to the south. Winds gusting up to 32mph until 3 A.M. Dew point temperatures around 69 all night. I think the clouds and wind would have essentially caused this evening to be useless for imaging. Visual observers would do better, but the scopes would have been bouncy and the transparency poor for much of the evening.

Friday, July 24 (No Stars)

If you would have hung around for Friday, ugh. The day was miserably hot and humid with a high of 99° and dew point of 70° most of the day. And then there were the thunderstorms and clouds to ruin the evening. A complete loss.

Saturday, July 25 (No Stars)

Well, wow. Hot, miserable day, then storms and clouds again. This completes one week of what might have been NSP 2020.

Summary

There were only 5 hours of imaging out of 25 possible:

Sun 😡😡😡😡😡
Mon 😡😡⭐⭐⭐
Tue 😡😡😡😡😡
Wed ⭐😡😡⭐😡
Thu 😡😡😡😡😡
Fri 😡😡😡😡😡
Sat 😡😡😡😡😡

It's even worse if you include the two additional washouts of Friday and Saturday: 5 good hours out of 35 possible, the equivalent of one good night in a week. It was a very good year to stay home; the virus didn't deprive you of much.

I hope to make it to NSP 2021! It has to be better than NSP 2019 and NSP 2020!

----------------------

Here's an example of problems with cloud reporting. This is not unique to Valentine, but is a consequence of how cloud observations are made in this era of automation by devices called ceilometers. A quote from an abstract for a 2016 study of ceilometer errors indicates the problem:

The limited areal coverage of ceilometers results in error when skies are heterogeneous, but these errors are small compared to those caused by the limited vertical range: observations of clear sky or few clouds are often in error as the instrument cannot detect the presence of upper-level clouds. [My emphasis.]

The hourly report for Valentine, NE on July 24 at 5:52 P.M. CDT. indicates CLR (i.e., clear) sky at 5:52 P.M. CDT.

A satellite image of Cherry county and Valentine taken four minutes later at 5:56 P.M. shows the sky is at least half covered with high clouds.

The position of the Valentine weather station is just south of the letters KVTN, at Valentine Municipal Airport.

Unfortunately it is often the case that clouds causing considerable extinction are completely missed by weather reports. This is partly by intent, as high clouds are not of importance to aviators.

The lesson here is: Don't assume the sky is clear because a station report says it is. It may in fact be unsuitable for imaging.