Finally, An Image!

 It's been three years since my last pretty image, not including the spectra. This is the first image taken with my transitional platform that's built around an AT65EDQ imaging scope, Losmandy G11G mount, and SBIG ST-8300M CCD. On the software side it uses APT, Stellarium, and PHD. 

I chose the Cocoon Nebula (IC 5146) and collected the following frames:

• Luminance: 12 frames @ 5 minutes each, unbinned, CCD cooled to -10C
• color filters: 12 frames each, 2.5 minutes, binned 2x2, -10C
• 24 dark frames at each bin/time/temperature combination used
  

I processed it using Images Plus and Photoshop.

Cocoon Nebula (minimal crop, scaled)

I'm really pleased with the performance of the G11G--the stars are nice and round. My processing left a lot to be desired, though. I clipped the dark end of the histogram and did not do a good job getting rid of the sky gradient; doubtless there are other shortcomings. But still, given that this was imaged through a white zone sky (Bortle 7.5) with only LRGB filters, I'm pleased.

Link to Astrobin page for this image

Next up is learning PixInsight, and with some luck the smoke will abate and I'll be able to travel to darker sites.

Smoke and the Nebraska Star Party

I registered and had purchased a park sticker. A few days before my planned departure to the Nebraska Star Party I assessed the smoke situation and decided not to attend. My personal judgement was that it wasn't worth the travel expense and hours of driving to seek out what would probably be mediocre sky.

Last night I was at a friend's house north of Minneapolis and the effect of the smoke was obvious. The limiting magnitude was around 4 instead of the usual 5.5. Extinction due to smoke was costing us somewhere around 1.5 magnitudes.  That translates as requiring exposure times to be 4 times their normal values.  

Looking at satellite loops suggests the smoke blanketed NSP the first three nights (Sunday, Monday and Tuesday nights). Wednesday night was probably the best of the event, but even then there were occasional clouds combined with smoke. Thursday night's forecast is for fewer clouds but more smoke. 

Considering the five nights from Sunday through Thursday, recent years have not been kind to NSP. In 2019 it rained four of those nights. If NSP 2020 had taken place it would have provided maybe five hours of good quality imaging, unfortunately coming as three hours one night and two another. This year's NSP 2021 may have been a complete loss for imaging unless you're willing to image through smoke.

I'm beginning to think I was spoiled by my first three NSP trips (2014, 15, and 16).

The question is if this is just a bad run of weather or an indication of some sort of "new normal" as the climate warms and wildfires become a regular feature of summer.

Time will tell. And while we wait, get fully vaccinated if you aren't already!

Get Vaccinated NOW.

Both my wife and I are now fully vaccinated: 2 jabs each and well past the time needed for them to take effect. It's very liberating after over a year of being in near-isolation! I can go to the hardware and grocery stores and shop -- no more curbside pickups. And it means when I'm ready I can hang out at the Club's dark-sky site and do some imaging.  My friends are all vaccinated so we don't have to worry about sharing the virus. In other words it's back to our pre-pandemic lives.

So if you're a vaccination holdout keep these little factoids in mind:

1. You're keeping health workers overworked because a certain percent of you will require hospitalization or you'll become long-haulers. Oh, funeral homes will also be busier because a small percentage of you will die.
   
2. You're already keeping the economy from returning to normal as fast as it might otherwise. This hurts everyone, including you. Have you been complaining about how "overreaction" to the virus has hurt the economy? That's what you're doing now.
   
3. You're placing at risk those who vaccination might not protect sufficiently. Remember, it's only 95% effective, and possibly less against variants. Know anyone with COPD or is on chemotherapy? Pass the virus to them and you will be responsible for the suffering they will endure.
   
4. Speaking of variants, you're doing the virus a favor by helping it hang around and create even more variants.
5. If you're holding out because you think there are "microchips" in the vaccine or it's some other kind of ludicrous plot against freedom or whatever...get some professional help because you've lost touch with reality.
6. What you're doing is following the very slow road to herd immunity for no reason. The people who will pay dearly for this are you holdouts and the few unlucky immunized people who you pass the virus to. The one thing you have going for you is that the crush of hospital admissions is now in the rear view mirror thanks to those of us who have gotten our jabs. You're welcome.
   

In other words, avoiding the jab is foolish and callous if not actually hypocritical and delusional. Good luck to you.

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

Some upgrades coming to my imaging system: I'm going solar! No more lugging two big heavy batteries around. Just one smaller one and a solar panel.  Even on a cloudy day it should be capable of replenishing the battery with enough power for another full night of imaging.

Also a new power junction box with a built-in dew controller.

On backorder and coming later this year is the big upgrade: an FSQ-106. Also a camera (ASI2600MM Pro) to replace my old SBIG ST-8300M. New filter wheel and OAG for it, too.

More about all this as it gets delivered and put to use!

Get Vaccinated!

I've now had my first jab of the Moderna vaccine. In fact, it was 20 days ago. The side effects were limited to a barely sore arm for about two days.  In eight days I get jab #2, and by April 20 I will be almost fully immune to COVID-19. I'm going to celebrate with a much-needed haircut.

After that I'll resume astrophotography from the club's Cherry Grove site and a friend's dark, relatively treeless back yard. And I'll be able to attend the Nebraska Star Party, too!

According to the WHO here are the people who shouldn't get a mRNA-based jab:

Individuals with a history of severe allergic reaction to any component of the vaccine should not take this or any other mRNA vaccine.

While vaccination is recommended for older persons due to the high risk of severe COVID-19 and death, very frail older persons with an anticipated life expectancy of less than 3 months should be individually assessed.

The vaccine should not be administered to persons younger than 18 years of age pending the results of further studies.

If you're not in one of those categories, then you have no reason to avoid the vaccine. 

Oh, you're not getting vaccinated because of something you've read on the internet? You've bought into the lies and bad science some people with political agendas are spreading? Fine, be a stooge. Chances are you'll only have mild symptoms if you get COVID.  Or maybe you'll have to spend a few days in a hospital bed, and then spend the next few years wondering if you're going to have chronic fatigue the rest of your life. No problem! At least you avoided the vaccine. Good luck to you and your loved ones.

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

Next time: I'm about to start a major upgrade of my imaging system: A new scope, camera, and processing software!

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

Follow-up: Our stimulus money didn't sit for more than a few hours in our bank account. Half went to Second Harvest, and half to St. Stephen's to help them assist the homeless. I hope you found a way to put your dollars to work for others, too. 

 

Donate Your Stimulus Checks

IF you are relatively untouched financially by the pandemic (and a large number of us have that good luck) you have a choice about what to do with your stimulus check(s). You could:

• Use the money to buy something for yourself, your family, or a friend.
• Save or invest the money
• Use the money to reduce your debt (mortgage, credit card, whatever)
• Donate the money
• Assist local businesses by buying their products or services
  

Those are certainly all good ways to dispose of the windfall and I'm not going to tell you one is better than the others; only you can make that decision.

I am going to encourage you to consider the last two options.

This pandemic has really hit the service sector hard, and particularly people whose earnings are lower. They've faced reduced hours, pay reductions, and complete loss of their jobs. In many cases they are trying to support a family. Eventually things will improve but while we wait for that they may be scrimping on food and medicines. One big way to help is to make sure they can find the food they need. 

Consider making a donation to your local food shelf. 

Further, there are those who are homeless, people who can't afford even the basic necessity of shelter during winter. Your donation can help provide them with a place of refuge. 

Consider making a donation to your local homeless shelter.

About that choice of patronizing local businesses? It's a good one, too. Many that serve the public have been forced to close in order to slow the spread of the pandemic. They've been asked to make a great sacrifice for the greater good. In other words, they're suffering financial hardship to keep you and your families healthy. At some point those of us they protected will want to show our appreciation, right? 

That appreciation can be in the form of our support for programs that will provide small businesses with relief. Yes, I know, that will mean raising our taxes, but don't small businesses deserve compensation for the sacrifices they're making on our behalf? I think it's safe to say keeping small businesses alive is a good thing. While we wait for those compensation programs to materialize:

Consider patronizing your local small businesses.

Sure, a new telescope or other piece of gear would be nice, but these are hard times for a lot of people. Pitch in and maybe more of us can make it to a better place together.

 

 

Getting started in Spectroscopy

The remainder of the pandemic (at least until there's an effective vaccine or treatment) will see me exploring a new aspect of astronomy: stellar spectroscopy.

Basically this involves imaging the spectra of stars. In my case I'll start with a diffraction grating mounted on the objective of a cameral lens. The grating produces a spectrum to the side of the star, like this:

I'm using a monochrome CCD camera. If you look closely along the spectrum you'll see little dark gaps in it. Those are real, not artifacts, and denote wavelengths that are being absorbed by the star's outer atmosphere. In the case of Vega it's hydrogen that's doing the absorbing, so the dark lines fall at known hydrogen Balmer wavelengths. These make it easy to calibrate your imaging setup, which is one reason Vega is recommended as the first star to image.

A spectrum like this can be analyzed with software. There are many software titles for doing this, I happen to use RSpec. Here is an example of RSpec output:

(This and all subsequent spectra were made with a 135mm SLR lens mounted on an SBIG ST-8300M CCD camera. An SA-100 grating was in front of the lens objective.) 

Five Balmer lines are clearly visible, allowing for fairly accurate calibration. Once calibration is complete it's possible to open a professional-quality spectrum of a star of Vega's spectral classification and use it to create an instrument response curve. This curve can be used to compensate for the way most sensors lose sensitivity away from visible wavelengths.

Once you have your calibration and instrument response done you're off and running. So what can you do? Quite a bit, but there are limits. You can't go too deep with a grating sitting in front of your lens objective; the SA-100 I use clamps the lens down to an objective diameter of only 21mm and your light gathering is greatly reduced. And worse, stars are converted into extended objects so the fraction of light going into the spectrum is spread over many pixels. This means your ability to look at dim objects is going to suffer unless you use long exposure times. (More about this later.)

Even with the limitation of an objective-mounted grating there are still interesting things to be seen with it.

Here is my spectrum of the star Gamma Cassiopeiae:

This is an emission star; it's thought to be surrounded by a decretion disk mainly made of hydrogen. The gas is excited and emits radiation at Balmer wavelengths. Notice at right you can see absorption areas caused by Earth's atmospheric oxygen and water vapor.

You can also get a glimpse of components other planet's atmospheres. Here are my spectra of Saturn and Jupiter:

When looking at a solar system object, you're basically seeing the sun's spectrum with absorption lines added by the planet's atmosphere. For these two gas giants one can see the absorption features in the sun's atmosphere (yellow labels), methane and ammonia in the gas giant's atmosphere (red labels and bars indicating the feature's spectral width) and absorption from the atmosphere of the earth (blue labels).

Presently I'm thinking about building a small collection of spectra for various star classifications. The problem with getting out to the really cool stars is that they tend to be quite dim. My first attempt to collect data for the Garnet Star (class M) required 240 second exposures. I probably should have used something more like 300 or 360 seconds.

On the subject of exposure times, I've made a little graph based on the objects I've observed:

Note this uses a log scale for exposure time. As expected, the required exposure time grows exponentially with magnitude. To get the spectrum of a magnitude 6 star I would need 17 minute exposures; to get down to 8th magnitude it's a 70 minute exposure! 

The way around this is to put the grating into the optical path of a telescope objective so that you can take advantage of the larger objective.That will be my next exercise.

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