Comet Lovejoy trials and tribulations

Friends have asked if I got pictures of the comet (Lovejoy C/2014 Q2) and I’ve been reluctant to admit, that, yes, I have, but that they are pretty bad pictures.

The first was a wide field shot in which I imagined seeing the comet’s tail streaming gracefully among the Hyades and the Pleiades. For tracking, I mounted the Canon 60Da piggy back on the Takahashi, set the camera’s intervalometer to take 60 1 minutes shots, and went in the house. About 10 minutes later, I let the dog out, and the sky had socked in, and was spitting snow!. So I shut things down, having got 5 minutes of usable exposure in. There’s the merest hint of a tail, if you look close, and really want to see it. I shot the images at 28mm, f/5.6. The comet is really small in the frame, although it would have worked ok if I could get more exposure. Actually I think the picture captures the impression you get with binoculars.

Comet Lovejoy Jan 14, 2015.  Canon 60Da; 28mm @ 5.6; 5 x 60 seconds.

Comet Lovejoy Jan 14, 2015. Canon 60Da; 28mm @ 5.6; 5 x 60 seconds. Click for larger image.

 

The next clear night I used the STL 11000, and was able to see really nice detail in the comet’s tail. Unfortunately, the camera was overdue for the annual regeneration of its dessicant plug, and the image is overlain by the shadows of tiny ice crystals. So I took a few pictures and set up for flat fields, hoping I could zero out the frost. The frost is a moving target, and the flats weren’t helpful. So the image below is 5 minutes, dark-subtracted and auto-background-extracted in Pixinsight. The black cuneiform is what frost looks like on a chip. You fix that by removing the desiccant plug from the camera, and popping it in the oven for 4 hours at 350 degrees, which I did the next day.

Comet Lovejoy Jan 15, 2015.  STL11000 on Tak FSQ 106. 5 min exposure.  With frost!

Comet Lovejoy Jan 15, 2015. STL11000 on Tak FSQ 106. 5 min exposure. With frost! Click for larger image.

The third try for Lovejoy was one of those completely abortive observing nights that nobody ever admits to. I planned to use the Canon at 100 mm piggybacked to get Lovejoy with the Pleiades, while exposing the STL11k for the coma and tail. First, the nut that holds the Canon to the mount had come loose and disappeared, and a spare was not immediately at hand. So, I scratched that part of the plan. Then, I could not find Lovejoy in the STL! I had collected coordinates in the house, punched them in, but no comet in the exposure. So I went online in the hut to get updated coords, tried them, and no comet. Tested the overall setup, and made a perfectly lovely, centered shot of Aldebaran. But I apparently had outdated comet info. It was around zero that night, and I was dressed for it, but my feet were getting cold and I was getting frustrated, so I hung it up for the evening with nothing to show for it.  That was about a week ago;  the forecast suggests that I may get another try on Thursday!

Pixinsight workflow for annotation

Since I’ve been using the Takahashi FSQ106-ED with the STL11000, I’m getting wide field images, about 3.9 x 2.7 degrees.  So the fields contain numerous cataloged objects that would be nice to identify.

Pixinsight offers a workflow to “solve” the image which provides accurate WCS coordinates that are added to the FITS header; and an annotation script that overlays  grid, constellation boundaries, and objects from several catalogs.

Sagitarius region

A wide field shot made with Canon 60Da and 28mm lens, about 45 x 30 degrees. Annotated in Pixinsight. 15 minute total exposure at Rancho Hidalgo, New Mexico.

For narrow field images, the ImageSolver script should work, but it fails pretty regularly on my STL11K pix and really fails on wide field shots made with the Canon 60Da with wide lenses like the one above.  Located in the Scripts | Image Analysis menu, the script panel asks for the center coordinates of the image, with a search function so you can choose a known object in the active image.  If the script fails, as is likely with wide field images, it is still useful to improve the accuracy of the ManualImageSolver script.  To use the ManualImageSolver script is not straight-forward, but it does work pretty well.  It’s not straight forward, because, before running it, you need to use the CatalogStarGenerator script to build a synthetic star field image; then use the DynamicAlignment process to manually match stars in the reference image (the synthetic catalog star image) to the target image (your astrophoto).  After saving the instance of DynamicAlignment to the workspace, you can run the ManualImageSolver script to provide WCS coordinates to the target image’s FITS header.  Honestly, you have to really want it.

Here are more details.  Open the target image, the image to be solved.  It must be FITS format, because the FITS header is where the WCS coordinates will live.  Locate a named object near the center of the image, you will use it the generate a CatalogStar image. I used M8 (Lagoon nebula) in the example. CatalogStarGenerator PanelRun the CatalogStarGenerator  located in the Script | Render menu).  Search for your chosen reference object, which will populate the coordinates fields.  Fill in the Dimensions field (from your target image) and provide the Image Scale info.  In the Stars panel, choose a catalog, probably the Bright Star catalog. The PPMC catalog is more comprehensive, but is too big for to be practical for wide field images Click OK to run the script, and it will build a reference image of the field. I use the STF panel (‘screen Transfer Function) to adjust the screen stretch so the stars are more easily seen.
Once you have a reference image you’re happy with, you align your target image with it using the

Synthetic star field

Synthetic star field made with CatalogStarGenerator.

DynamicAlignment process (located in Process | Image Registration menu).  When the process panel opens,  click the reference image (the synthetic star field); this defines the reference image for the process.  Then click the target image (your astrophoto).  Now click a star in the reference image that is obvious in the target.  This will place an X in the target that you will drag to the corresponding star.  The first few alignment points can be surprisingly painful, but once 2 or 3 points are correct, the rest are (usually) placed pretty accurately.  However, you MUST check each point since there is generally some distortion  in the field.

dynamicAlignment_screen

Screen shot of DynamicAlignment showing first alignment point.

The other pain point is that for best results, you really need 40 or so points spread over the target. (A shortcut is to use 4 or 5 alignment points and then run ManualImageSolver  followed by ImageSolver, which should run happily and produce a pretty good result.)  Ok, so you when you have enough alignment points, drag an instance of the DynamicAlignment to the workspace.  The instance is represented by the little triangle at the lower left of the process window; when you drag it to the workspace it creates a savable icon with all the details of the alignment session.  You need that when you begin ManualImageSolver. located in Script | Image Analysis menu.

ManualImageSolver script panel.

Manual Image Solver script panel.

Select your DynamicAlignment instance with the Control Points icon, and the catalog star reference image as the Reference Image.  You can improve accuracy by raising the Polynomial degree to higher numbers.  The residuals image provides an accuracy check; the distortion map shows optical distortion, and the distortion model provides a way of modeling the system to simplify solving other images with the same optical setup.  Anyway, now that you have manually solved the image, a set of WCS coordinates have been inserted into the FITS header.  And you can run the AnnotateImage script in the Script | Render menu.

Annotate Image script panel.

Annotate Image script panel.

The script panel provides an essential preview tool which lets you play with settings without rendering the whole image.  You will want to try different settings on labels and markers, but a tip is to use the Graphics Scale slider at the bottom to change everything at once.  You can render to a new annotated image, or a transparent overlay.  There are issues with label crowding, and it is easier to edit an overlay than the rendered image.  It’s still not easy.  You could render the grid and the labels into separate overlays which would make the text labels easier to work with.  I guess I prefer the transparent overlays, and accept that labels will be crammed together.  When you have your overlay, you can apply it with PixelMath.

PixelMath setup to add overlay to background image. I guess I normally would check  "generate new image" instead of "replace image".

PixelMath setup to add overlay to background image. I guess I normally would check “generate new image” instead of “replace image”.

All you need to do is add the overlay image to the background image.  Use the Expression Editor to select images from the workspace.  Here’s a detail of the result. detail_sag_annoteation

Accuracy is pretty good. I fear the label crowding is inevitable with this wide of a field.  Manual Image Solver is one of the tools in Pixinsight that is actually really well documented, as is Image Solver.  For the straight poop see http://pixinsight.com/doc/scripts/ManualImageSolver/ManualImageSolver.html

 

 

M64’s unusual dust feature

We had a really clear night June 3rd, following a cold front, so I set up an imaging run on M64, the descriptively named “Black Eye” galaxy.  I got a good hour of luminance data, but only about 15 minutes each of RGB.  I haven’t made anything acceptable with the color data yet, but the luminance is ok.  M64 (aka NGC 4826) is a crowd-pleaser  for amateurs because it shows visible structure in modest scopes due to its startlingly obvious dust lane.

M^$

M64 (NGC 4826), exposed 6-3-2013; luminance 12 x 300 seconds. 12″ LX-200 at f/10 with SBIG ST-10XME, resolution .47 arc-seconds/pixel. Click image for larger size.

But the dust lane wants an explanation.  It’s located at the inner third of of a broad disk, and is obvious even at the fairly broad angle at which the galaxy presents itself.  The outer disk has suggestions of spiral structure, but the details have apparently softened over time.  The explanation is probably related to the observation that the outer part of the galaxy includes a gas disk rotating in the opposite direction of the stars and gas in the inner disk, presumably from accretion or collision at some time in the distant past.  From  a paper by Corsini, E. M.; Bertola, F,  “The Phenomenon of Counterrotation in Galaxies” (http://adsabs.harvard.edu/abs/1998JKPS…33S.574C):

This galaxy contains two nested counter-rotating gaseous disks.  Radio and optical observations revealed an inner disk of about 1 kpc radius containing ~107 solar masses in HI and  ~108 solar masses in H2 and a counter-rotating outer gas disk extending from 1.5 to 11 kpc and containing ~108 solar masses in HI.

 

They are coplanar to the stellar  disk. Stars co-rotate with the inner gas  but beyond the dust lane less than 5% of them (~108M ) co-rotate with the outer gas.  The kinematical features of NGC4826 are interpreted considering an original gas-poor galaxy with prograde gas which slowly acquires a comparable mass of external retrograde gas.  The new counterrotating gas settles in the outer parts of the stellar disk,leaving undisturbed the galaxy morphology.

The galaxy is now relatively isolated, so there is no obvious smoking gun.  The culprit may have been a counter-rotating dwarf galaxy in orbit around M64, which has now completely lost its identity, and is suggested only by the Black Eye.

 

 

A nice triple conjunction

After the crazy weather we’ve been having , it was a treat to see Venus, Jupiter and Mercury crammed together into a neat triangle after sunset.   Mercury can be hard to find in the twilight, and it sure makes it easier to have Venus or Jupiter as a marker.  Tonight we have both!  Mercury is the faintest of the three, at the top of the triangle.

Venus, Jupiter and Mercury form a nice triangle May 26.  Canon 60Da 135mm lens, 1/60 at 5.6.

Venus, Jupiter and Mercury form a nice triangle May 26. Canon 60Da 135mm lens, 1/30 second  at f/5.6.  Click for larger.

A look at M99

I intended to get a good hour in for LRGB on this, but as it turned out the guiding was intermittent and I really only got 4 each good RGB frames for 20 minute total exposure.  So the image is not deep.

M99

M99, exposed 4-13-2013; RGB each 4 x 300 seconds. 12″ LX-200 at f/10 with SBIG ST-10XME, resolution .47 arc-seconds/pixel. Click image for larger size.

I’ve started using CCDStack and, when calibrating the frames, was getting a “negative ADU” alert when applying the flats.  This was quite mystifying.  It turns out I was not making flats with enough exposure. I resolved it by re-exposing the flats with the 40 watt bulb (instead of 15 watts), increasing the exposure so I was getting about 60% full well capacity.  That satisfied CCDStack, and should make a better flat. I’m still seeing irregularities in the background areas, which were repaired in Photoshop with Astronomy Tools from ProDigital Software.

M99 is a “grand design” spiral, except for its crazy arm which has presumably been distorted by a close encounter.  Because it presents itself so well, it’s been the subject of a lot of research, mainly concerned with the distortion of the spiral. This gets interesting because HI (neutral hydrogen) mapping from Areceibo showed a massive (about 100 million solar masses) rotating accumulation of neutral hydrogen fairly nearby, dubbed VirgoHI21.

Wikisky screenshot of M99 vicinity

Wikisky screenshot of M99 vicinity

There’s nothing to see of Virgo HI21, it seems to be mass without stars, which only shows up in radio survey.  From its mass, it should be a 12th mag galaxy.  The discovery of VirgoHI21 was greeted with great excitement, because it was thought to be the first candidate for a dark matter galaxy, which maybe it is.  Would that be cool!  But it seems that dark matter refuses to reveal itself that easily. Evidence is mounting that the VirgoHI21 is a tidal tail, probably from M99, the result of nearby NGC 4262 gliding thru the neighborhood 280 million years ago. This is all gleaned from the detail page on M99 from WikiSky.

NGC 4298 and 4302 are a lovely pair that I will image soon, if it ever clears up.

Orion and New Moon

We’ve had a rainy week and 5 or 6 inches of rain, but it cleared up nicely.  I planned a run on M99, which I had botched a few weeks before.  i unparked the scope, fired up the camera & coolers, opened the roof and aimed at Denebola to check the aim.  That accomplished, I headed inside to do the rest from the living room.

I stepped out of the Hut into a lovely twilight and had to just stop to take in the Big Picture, which is so often lost when futzing with gear.

The Hut in a lovely twilight. Canon 60Da, 38mm; 4 seconds and 1/60 sec exposures combined in Photoshop.  Our local ugly green gradient was cheerfully removed with the Astronomy Tools Soft Gradient removal action.

The Hut in a lovely twilight with Orion and our moon. Canon 60Da, 38mm; 4 seconds and 1/60 sec exposures combined in Photoshop. Our local ugly green gradient was cheerfully removed with the Astronomy Tools Soft Gradient removal action. The red wash was added by my headlamp. Click image for full size.

I heard peepers chorusing across the field and the  redwings calling in the bamboo patch. Then coyotes had a brief earnest discussion.  I haven’t processed the M99 frames yet.  Will put them up soon.

Supernova 2013am in Leo

In my continuing, ongoing shakedown, I set up a full LRGB series of M65 (NGC 3623) on the clear, moonless night of April 3. The forecast was good, so I set things running and went to bed. Somewhere in the green series, things murked up a bit, and the tracking crapped out for some of the greens and all of the blue.

M65 on April 3, 2013. 10-5 minute luminance exposures with LX200 12" at f/10 with ST10XME.

M65 on April 3, 2013. 10-5 minute luminance exposures with LX200 12″ at f/10 with ST10XME.

The luminance looked pretty good, except for the usual annoying, slightly oval star images.  But wow, quite by accident, the image shows Supernova 2013am, discovered on

Supernove 2013am

Supernova 2013am, UT 03:50 April 4. .47 arc-seconds/pixel

March 30 by M. Sugano (Japan).  I’m probably the only one who didn’t know this was now playing in one of Leo’s Kodak Photo Spots.  Still, hitting it by accident means I could have discovered it!  Well, if I had actually noticed it!  I found out about the supernova via a casual mention on a mailing list, and thought, “didn’t I just image that?”

Second look at The Eyes

I had a few hours before moonrise, and wanted another stab at NGC 4435 & 4438.  I  thought I had good focus, and was getting about 5.5 FWHM on the focus run, but it looks like the focus drifted quite a bit during the run. NGC 4435 and 4438; 5 x 300 with 12" LX-200 at f/10 and ST-10.

NGC 4435 and 4438; 5 x 300 with 12″ LX-200 at f/10 and ST-10.

And for some reason Maxim refused to connect to the mount, so the exposures are unguided.  I got 5 sort of acceptable 300 second frames.  NGC 4438 is one abused galaxy.  It seems likely but not certain that NGC 4435 is responsible.  From ESO (http://www.eso.org/public/news/eso1131/) :

“NGC 4435 could be the culprit. Some astronomers believe that the damage caused to NGC 4438 resulted from an approach between the two galaxies to within about 16 000 light-years that happened some 100 million years ago. But while the larger galaxy was damaged, the smaller one was significantly more affected by the collision. Gravitational tides from this clash are probably responsible for ripping away the contents of NGC 4438, and for reducing NGC 4435’s mass and removing most of its gas and dust.”

The dark patches on 4438 are enormous clouds of visually opaque dust.  I believe the fuzzy patch just to the right of 4438 is a small companion galaxy.

Sucker hole

For amateur astronomers, a “sucker hole” is when it looks clear enough to set up, but as soon as you’re ready to get started, it clouds up again, and you feel like a dope.  We’ve been waiting for Spring to get started for what seems like forever.  I first heard spring peepers March 9, and knew spring was at least a possibility.  But that was followed by weeks of mostly wintry weather  and several days of serious snowfall.  So for our little tree frogs, a day warm enough to chorus and mate might turn out to be just a “sucker hole”, and I’ve often wondered if the following cold snap is a nuisance or a disaster for them.  On March 26, I heard the peepers again; it was 31 degrees, and blizzarding giant flakes of snow.

Tonight, we had a few clouds around sunset, but it cleared up very nicely, so I opened the hut and hoped to get a few pictures before the moon came up.  I framed NGC 4435 and 4438 in Virgo (“The Eyes”) and set up a series of 300 second exposures.  I went inside and saw that the results were crap;  I went back out, and sure enough, alto-cumulus had moved in.  partly_cloudy_IMG_4598-2I collected 3 frames and processed them just to see what results you could actually get under really, really poor transparency, with strong moonlight illuminating the cloud cover.  The remarkable thing to me is that the galaxies are easily identifiable, including a suggestion of the distorted chaos of 4438 on the right.  4435-003L_c_crop

The image combines 3 – 300 second integrations, without very good registration.  The actual exposure is probably much less, with the clouds acting as a shutter.

Two of the Leo Trio

After I got a glimpse of Pan-STARRS, it looked like it would be clear enough to open the Hut.  I wanted to run some more v-curves (calibration runs) in FocusMax, but apparently I had the steps set too small and the center focus position set too far off.  So the run took forever and didn’t give a good curve.  Meanwhile I went inside and was working remotely and the network was uncharacteristically slow, in fact excruciating, so I went back out to the hut and worked from there.  TeamViewer was running at 90% CPU, which is not normal.  Anyway to salvage the evening, I chose an easy target that was far enough from the meridian to avoid mirror flop issues.  The “Leo Trio” consists of M 105, NGC 3384 and NGC 3389, a pretty tight grouping of obvious galaxies.  My camera field at 17 x 11.5 arc-minutes is a bit tight for all three, so I framed  3384 and 3389 and set up for 10 – 300 second exposures.

Two of the Leo Trio, NGC 3371 and NGC 3389.  8 x 300 seconds.

Two of the Leo Trio, NGC 3384 (left) and NGC 3389 (right). 8 x 300 seconds.

The stars in the subs are a bit oval in the  East-West direction, so something is not optimal with guiding, will work on that later.  I didn’t shoot RGB because the sky started murking up, and ended up with 8 ok luminance frames to work with.

After processing the image, mainly with Maxim’s DDP (“digital development”) utility, you can see what looks like the remnant of a central bar or disk not exactly perpendicular to the axis of the ellipse.  I was expecting an elliptical galaxy, but it looks like NGC 3384 hasn’t evolved quite that far yet.  NGC 3384Elliptical galaxies are considered to be the end state of possibly numerous galaxy mergers and are mostly found in crowded galactic neighborhoods, in this case the M96 group.  When I selected NGC 3384 from TheSky, it was identified as NGC 3371, and guess what, it’s both!  NGC 3371 was discovered Mar 11, 1784 by William Herschel and eventually listed as NGC 3384, then recorded Mar 23, 1830 by John Herschel and listed as NGC 3371. Apparently this is one of the ways that errors cropped up in the NGC catalog; the accepted name seems to now be 3384.  Depending on the source, it’s identified as an E07 elliptical, or occasionally as an SB0 (which is to say a lenticular galaxy with no apparent spiral structure but with a bar), which looks to be more accurate.  NGC 3389 looks like a beat-up spiral that has been distorted by a close encounter, and would be fun to add some RGB data.  It’s blue and has active star formation going on; from it’s motion and distance, it’s not considered to be part of the the M96 Group.