Tuesday, September 16, 2014

A Few Hours Under Dark Skies

Last weekend between hurricanes Norbert and Odile, which is scheduled to hit Wednesday, we had some pleasant weather.  With a nearly last quarter moon, and some new hardware to learn, I called buddy Pat, and invited myself out to his observatory near Benson.  It is always more fun to have a friend under the stars with you, plus he had experience with the auto-guider I was trying to learn to operate.

I'm still learning more about using the refractor obtained a few months ago.  The task for Saturday was to get the auto-guider working with the AP1200 mounting.  I always try to keep things as simple as possible out in the field, and the use of any auto-guider means using a computer - believe it or not, new for me as it requires a power beyond a 12 volt battery...  Melinda and I got a little portable notebook computer a couple years back that hasn't found a permanent application, so was going to try to run new software and hardware on a relatively new mount and scope - what could go wrong?!

Nearly all telescope drives have slop, periodic and alignment errors that limit tracking accuracy.  In the past, macho astronomer that I am, I'd normally guide manually when it was needed.  The image at left shows the little auto-guider I first used with Pat's setup in June.  Even with a scope so much smaller than the one shooting through, small pixels in the compact cameras and sophisticated software work at keeping the tracking nearly perfect for long exposures. 

And let me talk about digital cameras for a
minute.  Virtually all of the images taken in the 800+ posts here are taken with couple Canon DSLRs that I own.  Compared to olden days using film these newer cameras are a godsend!  No waiting for processing to find out the telescope or lens was out of focus, or poorly tracked, or object decentered.  The digital images go immediately in the telescope for stacking or further processing.  There are issues though - consumer cameras work great for most applications, but for long exposures, electronic noise is added to the signal.  Specialized astronomy cameras are cooled to reduce noise, separate dark exposures can be taken to minimize the noise, and many exposures can be averaged to reduce noise compared to the faint signals.  The exposures shown here were taken Saturday at Pat's.  At left is a full-resolution partial frame of Messier 20.  It is a 3.5 minute exposure with the TEC 140.  The red, green and blue speckles are actually "hot pixels" where some of the little sensors have more noise than others.  Fortunately, they mostly repeat really well, so darks can be taken separately, like at left.  This is the exact same piece of the sensor, so the hot pixels repeat in both images.  Check out the green clump of them above center.  The "dark" is typically subtracted to reduce noise in the object's image.

Most modern cameras have built-in tools that can help too.  My 6-year-old XSi, used for these images, has a "long-exposure noise reduction" feature.  The image at left was taken right after the above exposure, with that feature turned on.  After the 3.5 minute exposure was taken, it closes the shutter and takes a 3.5 minute "dark" exposure, which it subtracts from the object image before writing.  The result is an image with fewer of the hot pixels as above.  It has been shown that you are better off to take many "dark" exposures when not under dark skies.  Most consider taking the darks sequential to the object exposures as wasting half of your potential exposure time.  As long as I'm going after reasonably bright objects, I sort of like the convenience of doing this part of the calibrations in camera...

As demonstrated in these exposures, the auto-guider worked great!  After attaching the guide scope to the telescope, hooked it up to the notebook, focused, and calibrated, and it worked great, no issues at all!  I ended up taking 7 exposures with a total of about 25 minutes.  When stacked together with some levels and curves adjustment, the image is shown at left.  I'm thinking it looks pretty good for a consumer unmodified camera.  If I had taken the images with the 20Da (with slightly modified red response), the red part of the nebula due to hydrogen emission would have been more prominent.  The blue part of the nebula is from the hot blue stars near the center reflecting off the dust and gas clouds...

The moon came up shortly after 10pm, so it was an early night.  Just before breaking down the scope, I took a couple frames of the moon a couple degrees off the horizon.  Nothing special, but still fun to see what the nearly 1,000mm focal length scope can do.  Of course, it would have been better high in the sky, but it is a phase of moon I rarely photograph, so the fun was in the taking! 

It was a fun night - Pat helped me with some guider stuff, and I helped him with some collimation issues, so we both benefited by our company.  We'll likely do it again soon...

Monday, September 8, 2014

Sunset Rays

Tucson made the national news today with flooding caused by torrential rains - leftovers from hurricane Norbert that passed off the Baja coast a few days back.  The official rainfall at the airport doubled the previous record for 8 September with 1.84" today, but only the 9th wettest September day of all times...  Still, that is a lot of rain when 12" a year is normal!  Unfortunately, 2 women lost their lives locally in separate incidents when their cars were swept away trying to cross flooded washes...  It is about the second thing you learn living in Arizona, do NOT enter a wash with water running (the first is about using sunscreen).

The rain ended in early afternoon, followed by clearing from the west.  After coming home, I was doing cat chores about sunset when something a little unusual was seen in the west.  A thunderhead far to the west, below my restricted horizon here in town, was casting a shadow into the sky.  Called a crepuscular ray, it was really neat to see the dark searchlight shape cast high into the sky.  After running for the camera, I got a frame or two, unfortunately I didn't notice the continuation into the east (anti-crepuscular ray) in time to catch the ray's re-convergence.  I even went looking for weather satellite images checking to see if I could find a possible candidate.  There were some candidates in western Maricopa County, but I gave up after a bit.  Still, fun to see and observe the cast shadow!

Friday, August 29, 2014

Another Quick Trip in Search of Dark Skies

Our Summer rainy season is winding down.  Drier air and higher temperatures result as the weather pattern that brings the moisture moves elsewhere.  The result is blue skies through the afternoon, and with the moon still thin, I was tempted to make a run west towards Kitt Peak National Observatory for dark skies.  The program for the night?  Well, checking Heavens-Above, there was a pass of the International Space Station low in the south, passing the conjunction of Mars and Saturn, continuing towards the Milky Way.  That was a good enough excuse for me, so Melinda and I left during the height of rush hour to get up the mountain just before sunset.

Unfortunately, during the ISS pass, the sun was only 10 degrees below the horizon, so the sky was still bright enough that both satellite and Milky Way were barely visible, so am not even going to show it.  Had it happened 15 minutes later it might have been great!  Above is a 4-second test shot a bit before ISS came by - the planets and bright constellations are visible, but it was still too bright for the Milky Way.

Well, since it was a beautiful night and almost dark, what to work on next?  I'm a fan of dark dust clouds that become visible by obscuring more distant clouds of stars, and with the Summer Milky Way high in the sky, a perfect time to image some.  I was enamored of dark cloud complex LDN 673 in Aquila imaged by friend Adam Block with a 32" telescope a couple seasons ago.  You REALLY want to go to that link to check it out!  All the images I saw were of the dark clouds spilling out of the field, so figured it was worth a wide-field shot.  I set up a recently-acquired Astrotrac mount with my XSi and 200mm lens.  I was able to capture 9 frames of 2.5 minutes each, nearly 23 minutes of exposure.  With a moderate crop of the stack, shown at left, the dark complex is barely seen at center, with LDN 684 above it near the upper edge.   There is something to be said for 20 hours of exposure and a 32" telescope for Adam's shot, but a couple hours and longer focal length than my 200 would be an interesting shot too!

While the above shot was exposing, I also broke out another tracking mount, a smaller Polarie on a sturdy tripod.  I installed my "antique" (nearly 10 years old) Canon 20Da camera with a Nikon 135mm lens.  The 20Da works well on emission nebulae, so with the Milky Way still high, I chose to go after an interesting nebula, the Cat's Paw nebula, NGC 6334.  While a small nebula, it sits in an interesting part of the Milky Way.  It is low though, barely over 20 degrees off the horizon at its highest and already was lower than that.  I got 8 frames with the 135mm lens at F/4, combined and shown here (20 minutes of exposure).  The bright stars at left are the "stinger" of Scorpius.  The lower reddish cloud is the Cat's Paw Nebula, the upper red hydrogen cloud is NGC 6357.  There are a plethora of other objects in the field, certainly many dark clouds, so I was happy.  There might be a hint of greenish glow from natural airglow, shooting so near the horizon...

I promised Melinda we wouldn't be out late (she wasn't feeling great), but I really wanted to try to catch a bright comet that was in the evening sky.  Comet Jacques, C/2014 E2 is currently not visible to the naked eye, but is easily spotted in binoculars.  It is moving quite quickly though - its motion was visible even in binoculars over the period of 15 minutes!  While the color was not seen in binoculars, even a short exposure shows the green color of dissociated carbon molecules of the coma.  This is a 3-frame stack, barely 7 minutes total exposure centered on the comet.  There is a barely-imagined straight ion tail going off to the upper right.  There is a blurred red nebula at right center as well, I believe it is Sharpless 2-155, the Cave Nebula.  It looks pretty bright and would likely make a good future telescopic target.  Comet Jacques is getting further from the sun, but closer to the earth - it will stay just below naked-eye brightness, but should be visible for the next couple months...

Even with all the observing we got in, we were home a few minutes after 11pm, not bad for a school night!

Wednesday, August 27, 2014

Illinois Leftovers!

I just realized there were plenty of images from our recent Midwest trip that hadn't made it into the blog and really needed to...  It is always amazing to me to see the change in vegetation from one trip to another a month or two later.  Certainly through the end of July when we were there, about the most common prairie flower was Queen Anne's Lace. It is a striking plant, and reading about it, is quite amazing.  I didn't know, for instance, that the common carrot we eat was cultivated from the plant, and is often referred to as a wild carrot.  Also now known is that it is not native to the Americas, but was introduced from Europe and is considered an invasive species!  The exposure at left is of a large flower not far from our house near the Fox River, over 15cm (6") diameter.  Shown in cross section, the diagonal struts support the umbel (think umbrella!) floret arrays.  Interestingly, the red center flower is seen below the umbel surface and is seen in the profile.  This exposure is a 3-frame focus stack, combined in Photoshop.

The name "Queen Anne's Lace" is from both its lacy appearance, and from the normally present single red bloom in the center said to represent a droplet of blood from a needle prick in making the lace.  The namesake Anne is said to be the queen of England or her great grandmother Anne of Denmark. 

With the exception of the singular central red blossom the open flowers around our place are pure white when open.  But as shown at right, the opening flower shows a rim of pink before fully open.  Both right and left images are single exposures taken on a windy day...

While walking through some of the rehabbed prairie areas, the variety of flowers was pretty stunning, and some forms that were unfamiliar to me.  Unfortunately, my book of native plants and flowers are 1900 miles away, and Google wasn't of much help, so I can't name this one.  Other than sharing their lavender color, you are on your own.  The left image was taken along the Fox River, and is a 5-frame focus stack. 

At right is what I believe is Monarda fistulosa, from the mint family.  Every trip back, it is like my eyes are opened to new species, and I do not remember seeing these firework-like flowers before.  But they are quite striking and the cause of some of the lavender-colored blobs in the background of the image in the preceding paragraph.

In closing, there were some quite nice thistle blooms along our property line with our neighbors to the south.  All flowering plants were popular with the pollinators, and this bumblebee was having a field day.  Of all the frames I took (many, since he seemed content to feed while I shot) this is my favorite with both the blossom and bee in profile.  Too active for multiple frames to focus-stack, this one caught much of the flower and bee in focus, including his grappling hooks on its legs...  Use of the on-camera flash was essential!

I think I've just about exhausted the images from our July trip.  We're already thinking of a return for September.  I suspect the Queen Anne's Lace will be long-gone, but the goldenrod should be in season, and who knows what else.  Whatever it is, I'm looking forward to it!

Tuesday, August 19, 2014

The Fall-Back Plan...

Even though the months of July and August are Arizona's rainy season, threatening precipitation most every day, the Kitt Peak Visitor Center continues to run its Nightly Observing Program on weekends.  While rare, occasional clear skies do happen, and I offered to fill in for one of the guides who needed to leave town.  Not unexpectedly, the high chance of rain caused the program to be cancelled, but ready for any excuse to get out of town, Melinda and I decided to head up for a few hours.  So 5pm found us pointing the car westward, even as a storm moved into eastern Tucson...

Usually for a session like this, I make some sort of plan.  With the high chance of rain, when at a higher elevation, observing the storms themselves can be very interesting.  There was also a -5 magnitude Iridium Flare once it got dark if it miraculously cleared.  And the fallback to the fallback plan was to hunt for glow worms!  On several occasions, twice in the last year, while walking along the paved lanes on the Observatory grounds, I've spotted bio-luminescent glows.  Upon closer examination, they came from the tail of a 4cm (1.5") segmented caterpillar!  In both instances, I didn't have a camera on me, so I wasn't able to document them, and contacting a couple insect experts produced shrugs over the Interwebs...  So I was going prepared this time, hoping for another encounter.

Arriving just before sunset, we found partly cloudy skies and the 20" telescope dome open with my boss in residence.  He and other staffers had worked on electronics and he was about to start on the pointing model for the software.  While the weather was clearing on the mountain, there were impressive thunderheads over Tucson with abundant flashing from lightning.  Shown at left is the cloud buildup illuminated by the fading twilight as the lights of Tucson start to come up.  Strikes like this are easy to capture with a tripod mounted camera and intervalometer.  By taking 20 second exposures every 25 seconds, there is a very good chance of catching some flashes.  All three of these strikes happened simultaneously...

With the clearing skies and the Iridium Flare appearance approaching, we retired to the car to set up my tracking mount.  With a wide angle lens, it can take more than a minute or two for the satellite to traverse the field, so I chose to track the stars so they would be points rather than the trails from a rotating earth with a naked tripod.  And since this flare would appear to be in the Milky Way, I chose my older Canon 20Da to try to catch some red-colored emission nebula.  Unlike normal, I was fully set up with minutes to spare, and actually got to try some test exposures to make sure framing and focus was set.  The Iridium satellites start out very faint, but I spotted it early before it entered the field, and it slowly climbed in brilliance as it reflected sunlight down to us off one of its antennae.  The exposure shown here is 3 minutes in length, with a Nikon 20mm set to F/4, and I thought it came out pretty well!  The Summer Triangle dominates the field, Vega at top, Altair at right and Deneb left center.  Just below Deneb is the red ghostly glow of the North American Nebula, named for its shape.  The irregularities in the glowing Milky Way are from dust clouds along the plane of our galaxy, and detecting them is one of my favorite activities...

Even as the lightning storms grew in intensity to the east, the glowing clouds of the Milky Way seemed to be calling to me.  Since it has been June since we'd seen these starclouds at the Grand Canyon, I decided to shoot a few frames to make a little mosaic of them.  Shown are the 3 frames, each a 3.5 minute exposure with the 20Da and 20mm lens as above.  While Photoshop can assemble them, Microsoft ICE did a better job for me, especially in joining the seams of the frames.  I love this time of year with all the dark nebulae seen in silhouette, and interestingly, another satellite was caught just below Altair, the bright star seen upper left.  The dashed trail indicates that the satellite was tumbling, varying in brightness.

After the frames were taken for the mosaic, I pointed the camera to a single spot and let it expose while I went off in search of glow worms...  The lightning flashes continued unabated, and I was unsure the frames would be usable, but hey, as long as we were there, keep on exposing.  Melinda retired to the car as I went on a jaunt looking for glows...  And wouldn't you know, 100 meters into my walk, in the shadow of the 2.1 meter, I saw one!  While shining my red flashlight along the road keeping an eye out for snakes in the dark, I saw a flash, then another.  I dropped my sweatshirt I'd brought to kneel on, and took a closer look.  As I got closer, it glowed intensely, and I saw it was a different worm all together!  It looked to be a small inchworm, about 2cm long and less than 2mm diameter, much smaller than the segmented caterpillar I'd seen before!  I fumbled to put on the macro lens, turned back to it, and poof, it was nowhere to be seen...  It got away, dug under a layer of dirt and escaped my gaze.  But I saw it and now I've got 2 species to find instead of just the one...  I continued the search, but didn't find any more glows in my amble.  But I didn't go away empty-handed...  With the summer rains in full force, the mountain was covered in Sweet Four O'clock flowers, an evening-bloomer.  With none of the domes open yet, and numerous lightning flashes filling the air, I took a flash photo at left without any guilt.  There were also huge clumps of datura, also night-bloomers.  I've posted about these before, with pictures just a mile or so below the Observatory.  These were some healthy stands atop the mountain, and though I didn't spot any pollinators among the numerous flowers, I had to take an image, shown at right.

I promised Melinda I'd have her home by 11:30, so I finally concluded my glow worm search, broke down my still-exposing camera and platform and headed down the mountain.  Interestingly, all of my "programs" saw some action - flare, storms, stars and glow worms were all successful to some extent.  Fun, fun, fun!

Saturday, August 16, 2014

TEC Testing!

A couple months ago I invested in a like-new TEC 140 telescope.  The 140 in the model refers to the aperture in millimeters (5.5" diameter).  Its beefy nature required me to acquire a similarly beefy mount for it - I ended up making one using locally obtained materials, and a local welding shop.  As a reminder, it is a simple Altitude/Azimuth mount, shown at left.  Travel and summertime monsoons have conspired against me in getting it out under the stars, except when visiting buddy Pat a few hours one evening . The other day I left after getting home from work to check out the performance of the new mount/telescope combo.

My favorite vantage point is a quick trip to "A" Mountain, or Sentinel Peak, which offers an unparalleled view of the downtown Tucson area.  It is an easy drive there for daytime access, and gains a few hundred feet elevation for "testing" telescopes!  At right is a 2-frame mosaic with labels showing the location of the 3 shots referenced below.

First up was the old Pima County Courthouse, its scenic dome nearly hidden behind the taller court and government office buildings surrounding it.  But I know where to look to find it and it is a rewarding sight and target for testing.  The spectacular tile work was easily seen and sharply resolved  for being 1.4 miles from my location.  This view is shown at full-resolution, and was not down-sized for the blog. 

A good test for color errors in a refractor is to include bright lights in the field of view.  I found some at the UA football practice facility 3+ miles away.  If the TEC were not excellently color corrected, blue or purple halos would have likely been seen, but none can be spotted in this view, again, shown at full resolution.  This view shoots past the field into the Sam Hughes neighborhood as well.

Finally, I took a 2-frame mosaic of St Augustine Cathedral, located just south of downtown.  The left view shows this mosaic, and the right one shows part of it at full resolution.  I can't find any fault with the optics at all.  The mount was producing a little vibration in the considerable breeze atop "A" Mountain that afternoon.  I'm thinking that the interface between the mount and Gitzo tripod could be improved, or a more stable telescope tripod might be stiffer.  In any case, these images show the scope/mount combo works great and I can't wait to get it out again...

Sunday, August 10, 2014

Keeping Astronomers Hours!

As I prophesied a week ago when we returned from the Midwest, our Cereus repandus on the east side of the house has been a busy plant lately.  Past observations have revealed that a pinky-fingernail sized bud transforms to a nearly 14cm (5") diameter flower in 8 days!  Last night was the 3rd consecutive night of blossoms, but nearby storms and gusty winds made any images difficult, but I had a setup out the 2 preceding nights.  I've done the time-lapse thing before, and documented the transformation from bud to flower to pollinators, so what to do this time with the abundance of riches before me this time?

My decision was to take a detailed census of the night-time visitors that came by the flowers during the night.  Shooting a frame every 3 minutes (used on the time-lapse above), makes it likely that some will be missed, so the frame rate was moved up 6X to 30 seconds between frames.  The flowers don't open fully till about 10pm, so started about then, going to nearly sunrise at 5:30.  Yes, that is a lot of pictures (1672!), and most just show the lonely blossom, but some show more, and that is the purpose of the exercise!  At left is shown the "standard", mostly repeated 730 times the first (Thursday) night.  Of the two flower open that night, this one was about 50cm (20") off the ground - the other option was about 200cm (7 feet) off the ground!  My Canon XSi was used with the kit 17-85 lens shot at 55mm focal length, F/9 with the on-camera flash.  A third party intervalometer was used to trip the shutter every 30 seconds.

While was watching TV inside, I didn't have long to wait!  Ten minutes after starting the series, the first moth came by.  And it didn't mind the flash, hanging around for at least 90 seconds (three frames).  They are assembled together here at left.  This one didn't mind digging deep for a taste of nectar!  Click on the frame and you will note the little slit visible near the tip of the wing.  As shown at right, this same moth Note the wing slit!) returned 30 minutes later for a single frame.  While not visible in the left images, this shot shows the yellow side spots, identifying it as Manduca rustica, the rustic sphinx moth.

It was then quiet for a long time...  Some 3+ hours later elapsed until the next visitor came by at 3:15.  Another Sphinx moth, this one showing off his proboscis and head details.  Note the absence of a wing slit, so this one is a different moth.  Hard to say if the flash frightened him off or if they can feed in under 30 seconds.  Certainly the 3-frame set above, with its head buried in the flower might not have  been as distracted by the flash of light. 

Photos were taken until 5:15 am Friday morning, when the intervalometer stopped - nothing else was shown...

The following night (Friday), the flower opening was at eye level, about 180cm off the ground.  I decided to look face-on into the flower for a different perspective.  I started the sequence a little earlier, right at 10pm, and had to wait a little longer till Midnight for some action.  Thhis reveal is another rustic sphinx moth, with wings on full display, showing his large size.  I measured the flower later at 14cm (5.5"), so the wingspan is a good 12cm (5").  In order to get it all in I downsampled the image, so resolution is lost in the left frame.  The right image is shown at full resolution for maximum detail.  Antennae are folded down, and it sports what look like rabbit ears, also folded down, but might be an artifact of the coloration pattern.

A minute later another spotting, likely the
same moth was seen hovering over the flower inserting its proboscis.  It is slightly out of focus as it is too close to the camera, but if you look at the frontward of the orange-yellow abdomen spots, the upper edge is whitish as the above shot.

Fifteen minutes later, another spotting, but much more out-of-focus, so more difficult to do an identification.  for what it is worth, the proboscis, which is nearly in focus, shows a kink about at the end of its front leg.  Interestingly, in the left image, the is a kink in about the same place, so there I a chance that all three of these images are likely the same sphinx moth...

Well, that was the end of the moth appearances, but no the end of the activity.  At 5am, suddenly a spider is seen working on a web off the edge of the flower.  It has some resemblance to a huntsman spider, but I read they generally don't spin webs...  While the spider itself only appeared in one frame, the web was there the rest of the night, the flower petal it was attached to slowly bending as the above section of the web was finished and tensioned...  The web extends up 120 cm (4 feet) to the eave of the house, where it still stands.  Hmm, what might it have been trying to catch???

At 5:15 (interestingly the time I stopped taking frames the night before), it is like an alarm went off and the blossom was attacked by honeybees!  It was rare for a frame to catch less than 3 or 4 bees in the picture, often many more!  This effect is visible in the time lapse referenced in the first paragraphs time-lapse link.  From 5:15 to sunrise the bees fed hungrily.  It is interesting to note their full pollen baskets on their rear legs, even those who first appear at 5:15.  One of the frames, shown at right, looks to show a couple of intoxicated bees taking a break as they lie on their backs taking a rest before resuming work...  I never spotted any of the bees struggling with the spider web, but the location of the web might have been chosen for that purpose!

And as the twilight grew and the sun came up, the bees halted their visit too and the flower closed up and the night was over.  Very few other pollinators were spotted - I saw what looked to be an iridescent green bee of some sort, very tiny and out of focus, but mostly bees and sphinx moths, but it was fun to do the census and see what all came by during the night.  There appear to be an abundance of these night time bloomers around, and while the absolute number of these moths are small, hopefully the food source will increase as more plant these cereus.