Imaging at the 4M

The 4M is the MAS (Minnesota Astronomical Society) Mini Messier Marathon. It takes place annually during the fall when it's the second time of the year one can see a large number of Messier objects in one night. In Minnesota the fall marathon usually has much nicer weather; in spring, the observing field can be under a foot or more of snow, or it can be a soggy mess thanks to snow melt. The wind chill can be -25F.

This year the 4M was very nice. Temperatures were in the 60s, the ground was soft but not too wet, and a gentle breeze kept the dew from forming. Mosquitoes were at a minimum--I noticed only a few, and that was only during the early evening. Clouds spread overhead at sunset and persisted until a little before 10 P.M., at which time it was a scramble to get my imaging gear going before I lost too much more time on the southern objects I was going for.
Because the transparency was poor and time was limited I opted to go for only one of my southern targets, Sh 2-46, a fairly bright (LBN brightness 3) emission nebula in Serpens Cauda. With almost no time for it I opted to image it only in luminance. I had to end imaging after 39 minutes because it was sinking into the low-altitude murk and starting to lose brightness.

I stayed west of the meridian to get LBN 113, another emission nebula that almost three hours of Ha could not catch in my back yard. This time I went with a different plan, L binned 2x2 and RGB binned 3x3. I used equal total exposure times for L and RGB, 15x180s. The results were better than I expected:

Top: Sh 2-46. Bottom: LBN 113.

2-46 is the unimpressive light patch just below the center of the image. 113 straddles the yellow star near the image's center. The bright blue star to its right is theta Aql.

These took me to almost midnight, so the evening was still young. By that time M45 was well up, and a difficult object  I wanted, IC 353, was right beside it. It didn't take long to acquire the object and begin shooting. 

However, I made a bad mistake at this time. The scope and camera had to move quite a bit to swing from west to east of the meridian, and in that flip the camera's sensor plane went out of orthogonality with the optical axis. Focus was no longer anything like crisp across the field, and there was some astigmatism introduced. I should have checked everything over, but in my haste I didn't.

After I was done with IC 353, I was getting tired and decided to image something bright. IC 405 in Auriga was up now, and that became my target:

Top: IC 353. Bottom: IC 405 (Flaming Star Nebula)

IC 405 deserves more exposure time, but that will have to wait until another night. By the time I was done with 405 it was 2:44 A.M., and I was ready to call it a night. all but a handful of marathoners had packed it in for the night by this time, so I decided to join them.

Three of these are new AL Bright nebula list images for me, and the image of LBN 113 replaces my earlier attempt. I'm left with only one shaky image, in my opinion, that of Barnard's Loop. It's plainly in the image, but it could look so much nicer!

What's next? The seasonal dry spell in AL Bright Nebular list objects will last for another month or so. Things really start to pick up in November. If there are some clear nights another trip to Cherry Grove may allow me to pick up some fading summer objects. Cherry Grove is only modestly dark, but it's dark enough to allow LRGB imaging. 

PHD Version 2 review and the Little Dumbbell (Messier 76)

It's another time out for the Bright Nebula list this week. There was some discussion about polar alignment methods in our club's forum, which reminded me about the new PA wizard in PHD 2. Which reminded me that I hadn't upgraded from version 1 yet.

A few clicks later the upgrade was finished. The first time you start PHD 2 it will ask you to set up your default autoguiding configuration. You can create a number of configurations to invoke upon later runs, which can save some time. You'll need to know the name of the autoguiding camera you'll be using, the focal length of your guide telescope, and the way you'll be communicating with your mount. That last one is a little tricky. I tried ASCOM, assuming that because I connect the guider to my CGEM through the aux port. It turns out the correct option is "On Camera." My camera is an Orion StarShoot Autoguider, and the mini autguider telescope has a focal length of 162mm--A thank you to Orion for listing this in the product specs.

In point of fact, saving your time is what version 2 seems to be all about. When you start it, it will assume you're using your default configuration. You can do the camera and mount connection with one click or do them separately. (I experience some problems with the all at once connection, but I think this was a problem with the actual physical connection, not PHD.)

What follows is base on one experience using PHD 2. I'll be using it this weekend (fingers crossed for clear skies) and will update this with corrections if any emerge.

Start it scanning, stop it, select a candidate star, and you see the first surprise. The familiar green square is much smaller. I don't know if that's because of my short FL min guider, or is the case for all hardware.

As you did with PHD 1, you next click the little PHD icon and it begins calibration. Now the really nice surprise hits you... PHD 2 is fast! I didn't time it, but it takes probably 1/3 to 1/4 of the time the older version did. You'll be rolling in almost no time, so don't wander off for a sip of coffee or hot chocolate.

The gain control is more important now. If you switch exposure time the display may wash out in a way that might remind you of what version 1 did when it lost hardware connection. If this happens, adjusting the gain setting may restore the display.

And now the Polar Alignment Wizard. It's basically a camera-assisted drift alignment, which means the quality it provides depends to some extent on your patience. Here's how you use it:

1. Find a star at south azimuth that's near the celestial equator
2. Calibrate PHD using it. Center the star in your field of view and resume tracking it.
3. Start the wizard and allow it to watch the star drift (basically it will begin tracking with declination corrections disabled, and then watch the star drift in declination). It will try to estimate the rate and direction of dec drift. This estimate will bounce around for a while, but eventually it will steady itself--the greater your patience, the better your handle will be on the drift rate. 
4. Shift to Adjust mode, in which you change the azimuth of your mount. PHD gives you an estimate of how far you should move the mount, which is nice. I would suggest not moving it the full distance PHD suggests (indicated by a magenta circle).
5. Jump back to Drift mode (PHD will automatically reacquire your guide star!) and see if your correction was adequate. Chances are you'll have to iterate in order to get the right adjustment.

At this point you repeat the entire process for a star near the eastern horizon (adjusting the mount's altitude in this case). The instructions don't suggest recalibrating for the new orientation.

Chances are that at this point your alignment is good enough for long exposure photography. If you want it even better, repeat the azimuth process. If you have absolutely nothing else to do, iterate the night away until your PA alignment is almost perfect.

If there's a trick to this, it's the same one that causes confusion for the drift mode: The direction to adjust the azimuth and altitude for a northward or southward dec drift. PHD lets you enter notes to remind yourself of how this is done for your mount. If you've done drift before, a northward dec drift reported by PHD, indicated by an upward sloped red trend line, is handled the same way as a northward visual drift.

What PHD 2 PA offers is freedom from needing a reticle eyepiece; freedom from trying to establish the direction of dec drift, and a sort of entertainment factor as the program display shows the trend line being updated and the magenta adjustment circle resize.

One other feature that I think is a wonderful improvement is the ability to have PHD put the calibration start back where it was in your field of view before you started calibration. PHD 1 could often leave an offset. Usually this is so small that it's unimportant, but for long focal length imaging--like solar system imaging it can be a bother). I haven't tried this out yet, but when we get some planets back I will.

The image from two nights ago was M 76. Here is an improved version of what I posted on AstroBin:

Messier 76

This is a Ha/OIII bicolor image using almost six hours of data. The center is burned out, but because this is narrowband it's not actually saturated in the light frames. I'll try doing a reprocess to generate a less stretched version to act as a second input to Photoshop's High Dynamic Range merge tool.

Coming up on Friday, it's the fall Mini Messier Marathon. The current forecast is for clear skies! I hope to get some imaging done while others are hunting down Ms.

LBN 434 is a no-show.

Last night I went after two AL BN items, IC 1287 and LBN 434. 1287, a dim reflection nebula, was an almost hopeless task thanks to the trees and the very hazy sky. I collected some light frames, but not nearly enough. The frames were so bad looking that I haven't bothered to process them.

LBN 434 is a Lynds brightness 6 nebula, and I'm beginning to think that category 6 means anything dimmer than a 5. Maybe a better classification for 434 would be a scale extension to 7 or 8. Three hours of 5-minute H alpha exposures turned up nothing at all but stars and a couple of galaxies.

The object does show up in the Digitized Sky Survey, which is more than some cat 6 objects can say. (Evidently not all cat 6s are created equal.) After some work I was able to confirm that I was imaging the correct field. Processing the image beyond all reason might show a trace of the brightest part of the nebula, but it's not nearly solid enough to submit as acquired. The object was simply too dim for me to catch under my bright hazy skies.

I may go after 1287 from a dark site, but 434 is now on my list to not revisit unless I'm desperately short of objects on the way to the required 100.

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My mosaic of LBN 270 proved to be modestly popular on AstroBin, garnering more "likes" than any other image I've made.

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My next backyard target is going to be more fun, going after M 57 to image the outer shells. This will be a multi-night task, with a lot of unbinned H alpha work at various exposure times, and then possibly the same with binned color. I'll use my C 925 without its reducer/flattener for maximum scale, and because at f/10 the ring can sit happily within the central part of the field.

LBN 270 Mosaic

It's done. Spanning four nights (if you include one night's data that I eventually discarded because of poor focus), the four-image mosaic of LBN 270:

LBN 270

The irony of this is that I had to dodge a lot of clouds in order to image clouds. Only one night was clear for long enough that I was able to image two quadrants of the image.

Normally I would be imaging unbinned because of the short focal length used (an AT65EDQ at 422mm) and 5.4 micrometer pixels of the ST-9800M. Instead I did this by using 2x2 binning, which results in a speed gain by a factor of something like 3.6 (depending on who you trust as a reference). Each quadrant of the mosaic is based on about 20x300s light frames for a total time of about 6.6 hours.   

This is an object on the Astronomical League's Bright Nebula list. 

Speaking of which, a corrected list of objects that I made some time ago is now residing on the AL web site at:

https://www.astroleague.org/files/u3/BrightNebulaRev1.pdf

I might complain to the AL about getting no credit for this, but so far as I can tell they don't publicize this document.

The "official" list, still with errors, continues to be linked to at

https://www.astroleague.org/files/u3/BrightNebulaRev2.pdf

When is the AL going to fix this list? It's been over a year since the original posting of the list.

But enough about the AL, and more about the mosaic. I actually have two images I could append to the mosaic, one for IC 1318 (butterfly) and DWB 111 (propeller). The former is not oriented well, so I'm thinking that in a year I might revisit this and extend the mosaic down to Sadr so that it includes all of IC 1318.

But for now it's back to the list, and seeing how much binning helps tackle some of the dimmer objects on the list.

Time for Mosaics

I imaged many of the smaller/brighter AL Bright Nebula list objects in this season's sky last year, so this year I'm left to clean up the more difficult objects. These can be more demanding in terms of the sky I have to work with (tree-locked and bright), or by virtue of their larger size. In the former category are reflection nebulae and Lynds brightness category 6 objects.

Here's an example of the former, IC 4954 in Vulpecula:

This was shot in H alpha because it has a weak emission in that, and the narrowband filter helped to reduce the light pollution and moonlight. This is given a 2 for brightness.

For faint there's DG 191, shown in the previous post. There's no official brightness for this, but I estimate it as a Lynds 4. Most of it is visible in weak Ha emission, but the lower right quarter or so has a substantial reflection nebula component. Because I wanted to catch the blue tint I shot this in RGB. I should have gone with HaRGB, but I wanted to complete this in one night.

Sh 2-134 was too large for a single frame at 400mm. I combined two images to create a minimal mosaic using Photoshop:

I used Photoshop's default settings for this and it turned out pretty well. There is a transition line visible along the top of the lower frame, so it could use some reprocessing.

Next up is the huge LBN 270 (3 degrees across) in Cygnus, which will require a 2x2 mosaic. I managed to get the southwest frame last night during a couple of hours of clear sky!

Eventually I'd like to patch together a mosaic of Sh 2-240 (Simeis 147 in Taurus), a large supernova remnant in Taurus. That might take five or six frames!

Two star Parties, Two Images

A sad story.

First, the Iowa Star Party. Another year, another hot and humid run of days, even worse that last year. The weather forecasts were so bad (ditto the satellite loops) that I stayed home the first two nights. Thursday night reports were that there were at most two hours of observing. Friday night (the public night) it rained. Saturday it was hot, with the heat index hitting 113. Around the time of the before-dinner talk the dew point reached up to 82. The compensation was that the evening was clear, and I managed to get one image. Because of the extreme humidity my camera's sensor window fogged over at any temperature under 15C, which curtailed using it in a meaningful way. Sunday: l little cooler and drier, but still very warm and humid. The evening started clear (with clouds to the south from a thunderstorm over Missouri) but ended early when a thunderstorm to the northwest attained a high level of electrical activity--its lightning illuminated the sky to such an extent that observing or imaging was nearly impossible.

Out of four possible nights, one decent one.

Now on to the Northern Nights StarFest. Great Facilities. Amazingly enough almost no mosquitoes or flies. As might be expected for a forest setting, generally poor horizons. Wednesday night, clear, but absurdly heavy dew. One image as I fought the fogging sensor window problem. Thursday night: cloudy. Friday night: cloudy, Saturday night: cloudy with rain.

Four possible nights, one decent one.

No more star parties for this year, unless I opt to go to the Heart of America party. As nice as that one is, it's simply too far to go for a maximum of three nights.

In other news, SBIG sent me the ST-8300 sensor window heater and it was waiting for me when I returned from NNSF. It installed easily, and last night it seemed to work, although conditions didn't test it well. With it running, the camera went down to -15C, a good value for any summer night. It may have used a little more power than it used to, perhaps compensating for the heat source.

 I managed to image one of the objects on my list for ISP/NNSF: DG 191:

DG 191 and vdB 158

This was an ill-conceived RGB image. (I should have had the patience to do a multi-night HaRGB image. But it's just for AL, so it doesn't have to be frame-worthy, or even close.)

Another clear night on Friday? Sadly, the moon will be nearly full, so I'll collect Ha. IC 4954 may be the target.