Wednesday, March 30, 2016

double wanderings

As neither seeing nor transparency was especially good last night, I used my double star atlas to look at some random doubles.  I pointed the 12.5-inch at Alnath (Beta Tauri, though it is shared with Auriga) and used the slow motion controls to go to any nearby star which had a line through it on the atlas -- the sign of a double.  Some had a designation but others did not -- a signal that the pairing would be very close or of widely varying magnitudes.  The ballast I constructed on the back of my dobsonian base seemed to help cancel some of the vibration issues I had, and removing the counterweights from the back of the telescope tube helped the altitude fine control move freely.  Progress.  I didn't try astrometry as the seeing was too unstable; all viewed at 277x

STF719: widely separated with an orange A and bluish B

STF753: I thought this was perhaps a 3x system [it's not].  Bright yellow A and a fainter yellow white B.

STF764: two bright whites widely separated

Anonymous half a degree to the NE: orange A, faint bluish B, pretty close

Anon. 10 mins. to east of that: really close, just split stars; equal brightness; both yellowish but the A star is more yellow and a little more bright

STT117.  !! Wow!  Carbon star to the west in FOV.  OS is a bright yellow A and a small faint B.  Lovely, colorful field.

STF796: Pretty yellow and faint blue

Had a look at M37, always a treat.  It was the first deep sky object I found by myself, just two years ago.

Mil2: First time I've seen this designation, J.A. Miller, an American astronomer in the late 19th century.  Name lives on.  It was an easy find and split.  A white A and slightly ruddy B.

Seeing was getting better at this point...

Bright anon about 20 min. to east of Mil2: Did not split at 277x so tried 554x, but no clear split.  I suspected an exceedingly faint star below it in FOV, widely separated, but not certain.

Bright anon half a degree to NW of 136 Tauri: average star, very faint B comes and goes with seeing.

132 Tauri: Orange, bright, very faint B widely separated

STT66: Wide separation orange stars of similar brightness

Anon 1 degree to N: Is it a 4x system?  or a double-double?  Two equal bright whites widely separated, and perpendicular to those another pair, much fainter, about the same separation

STF749: Hair-split, equal brightness white stars.  Nice.

STF716: Equal white widely separated.

H V 114: Fairly widely separated; faint star a 3rd? [no].

Had a look at open cluster NGC 1746: a nice wide spread with scattered grouping; much better under a darker sky.

I ended the evening looking at Jupiter.  The NEB & SEB were very turbulent, with large dark rust barges and great loops of purple festoons cresting up like waves, especially from the NEB into the equatorial region.  There was even a dark tan barge in the NTB.  The north polar region seemed lighter, and more banded, than the south which was darker and more solid in color.  No GRS or lunar transits.

Friday, March 25, 2016

ups and downs

I had no specific plan for tonight; I was far too tired and frazzled from a difficult day at work to put a lot of effort into an observing session.  I relaxed with some low power views, lazily moving the scope while sighting through the telrad to find M37, M36, M38, M35.  M37 with its short intersecting arcs of bright stars garnished with faint glows of unresolved stars.  M35 with the large hole in its middle.  M38, rich and open.  M36 bright enough to see in the finder, but oddly sparse through the telescope.  I remembered this month marks the second year I took up astronomy, with the very 12.5 inch telescope I was using.

I moved over to M42 and clearly saw the pinkish, almost rainbow line of nebulosity to the north of the Trapezium.  The rest was greenish and heavily mottled.  I traced the two arcs which stretch out from the Trapezium and could tell, truly, it forms a bubble, but very faintly joined at the opposite end.  The whole sky was greyish with nebulosity.  I moved up to Sigma Orionis and was able to see four stars even at 71x.  I then continued up toward Zeta and then I saw the Horsehead.

Yes, believe it or not, B33 the Horsehead and IC 434, unfiltered, from my red zone back yard.  I had been paying attention to the greyish nebulosity in the area, and looking through the eyepiece while I used the slow motion spindle to move the telescope up from Sigma.  I could see a brightening in the nebulosity as it ran between two stars with a sudden cut off between those stars.  And there was the dark intrusion into that nebulosity which is B33.  It was glimpsed averted vision, and I could not hold it with direct vision.  It helped that I recognized the field and knew where to look; but it was there.  I excitedly put in my H-beta filter, but that actually hurt the view: it became to greyish and grainy, too unsettled to clearly make out the line of IC 434.  Back to unfiltered, and moving the scope up a little more to check my sanity and look for NGC 2023, the Flame, which was there as a mottled haze.  I must've been very lucky and hit a transparent pocket in what was not overall an especially clear night; though seeing was good.

Moving over to Jupiter, and switching to 277x, I instantly saw a reddish star on Jupiter's limb.  What a strange night!  It was just separated from the planet, and in fact the edge of Jupiter seemed to flatten just where the star was, as if to give it enough clearance to be seen.  I thought it could not be a moon, since it was at a higher angle (up in the southern pole region) and not in line with Jupiter's equator.  But as the minutes passed, I noticed more separation, and that the three moons which were visible were at a lower angle to the equator than what I might expect.  And in fact the star was an orange disk like shape, very similar to the moons.   So I finally decided this must be a moon, and the moons' orbits must be at some weird angle to earth to make them appear off kilter.  Sure enough, checking the position of the moons upon coming inside, I find it was Callisto, just exited from occultation behind Jupiter. 

And to my everlasting regret, I also find that just a few minutes after seeing Callisto's reemergence, but the deciding to pack it in for the night, Callisto disappeared behind Jupiter's shadow.  I could have seen this peek-a-boo for myself.  When will I learn to keep observing, and not come in too early?  Would that I could stay out all night, and not feel tired or have the daily obligations I have.

Thursday, March 24, 2016

surprise night

Yesterday afternoon Clear Sky Clock showed it would be clear.  But it is notoriously wrong for high thin clouds or fog conditions, which is what I saw upon arriving home last night.  The GEOS satellite I also checked didn't look promising, with a river of water vapor pouring in to the Bay Area.  So I didn't set up.  But, after dark, it was clear.  I've noticed how many times thin clouds will dissipate after nightfall; it must have something to do with the air temperature changing?  In any case, I set the 8-inch up and had a nice surprise night.

After poking around Orion for a while -- which is sinking soon after darkness now -- catching E-F in the Trapezium, I went after some Carbon Stars.  The seeing was average but the transparency was below average -- the sky lit up with haze from the rising full moon.  I barely made out what I thought was Alpha Hydrae; after confirming the field on the chart I made a long hop down to:

Gamma Hydrae: red in the finder, magnitude 8-9, sharply orange-to-red, brightest in a sparse field.  Though already evolved into a carbon star, it is younger than the sun, having started life with a higher mass it burned through more quickly. 

My next target, U Hydrae, was behind our neighbor's large pine tree, so I spent some time looking at Jupiter instead.  No transit events or GRS, but dark barges in the EBs and some darkening in the northern pole region. 

Back then to U Hydrae, which was red in the finder, and a bright orange in the scope, about 7th magnitude, with a faint but pretty double to the south at the edge of the field.  AAVSO pegs the magnitude at 5.5; I've never been good at estimating magnitudes but the poor transparency surely played a role in dimming what I saw. 

V Hydrae needed some more waiting to clear a branch, and when it did it was a nice deep red color, a tad orange, magnitude 8 (AAVSO says 9).  It has a B-V color index of +5.5 and is one of the reddest stars visible.

My last target was VY Ursae Majoris, but this was blocked by my own roof, so I spent time on the moon.  While it was supposed to be full I did notice some terminator way at the edge, and enjoyed a variety of interesting sights.  Slivers of light off the edge of the moon which, as time passed, grew extensions and arcs and became crater rims.  Ridges folded like an unmade bed.  Shadows of ridges on further mountains behind.  Copernicus was flat and spread its Medusa hair widely over the lunar surface.  At one point a bat flew in front of the moon -- it was small, and it took three or four seconds for it to make its jangled flight across.  It must've been half the neighborhood away.

I tried for VY Ursae Majoris again, but it was still hidden -- so I lifted the whole scope up and moved it back one foot to the edge of the patio, and could find it easily.  A bright orange-red, brightest in field magnitude 6 (AAVSO agrees!).  The moon too bright, and the transparency now sheeting fog, to see much more of the field. 

Friday, March 18, 2016

crater copernicus at 885x

That's what I saw last night, and it was amazing.

Seeing was similar to the previous night, with a 6-8 second trough where fine detail was fuzzed out, then a 2-3 second crest of very sharp and steady views.  885x is 77x per inch of aperture of the telescope (a 12.5-inch masked down to 11.5-inches) -- well beyond the commonly held maximum useful magnification figure of 50x inch.  So I guess I can stop worrying about the mirror's quality.

Copernicus was huge, and it took on a weight and body I'd never imagined.  Usually it appears flat, and only interesting for its terraces in the crater and the finely granulated particles of its ejecta fanning out across much of the lunar surface.  But last night, at 70.84% full, waxing, Copernicus looked like the stump of an ancient tree whose center had rotted out, but whose gnarled, many branched roots still gripped the lunar surface.  The crater walls were tall, with shear cliffs at each terrace level.  The rim was bright and curved sinuously.  The depth and physical presence of the thing was astonishing.  Nearby Eratosthenes too was bulky, as if built up out of clay.

None of my moon books give a photo showing what I saw.  The Kaguya Lunar Atlas has a very nice image on plate 49, which show the ribbon like crater rim, but it doesn't show the height of the thing.  The Hatfield Photographic Lunar Atlas plate 5b is pretty good, but the depth is only hinted, and it does not show the ropey hills and ridges which make the outer sides of the crater, which I can only liken to buttress roots around a large tree's trunk.  I like plate 5b because it shows my Lunar Eagle feature to the east of Eratosthenes, on the near edge of the Montes Apenninus.  I think Rukl plate 31 comes the closest, though this is a drawing.  There's not much sense of the crater's depth but the ropey, veiny ridges radiating around the crater are more distinct.  It's only a little larger than the field of view I had, too.

A terrific view.  Next time the seeing is as steady as that, I'll be sure to pump up the magnification again.

Thursday, March 17, 2016

same four

I looked at the same four objects as last night: Iota Cancri, Beta Monocerotis, the moon, and Jupiter.

My separation estimates seem to be on track.  I tried position angle last night and they are way off, by 20 - 40 degrees.  I think it is some fault in how the pointer is attached; will try again tonight.

The moon was amazingly clear with lots of contrast last night, 553x and I could've pushed it higher.  I noticed my Lunar Eagle once again, very distinct.  In all the moon looked very substantial, with a weight and shape to the physical features, as if it was a beaten clay object.  And near the tip of the terminator there were successive waves of ridgelines with one final mountain range disembodied from the rest of the sphere.  A remarkable view.

Jupiter held 553x pretty well.  It was noticeably more orange than last night, which was more yellow.  The NEB was considerably darker than the SEB, but the southern edge of the SEB was pretty dark, and the SEB itself had a long thin barge of lighter material nearly splitting it in two.  The GRS was near the limb when I started viewing and had moved about half its width further away from the limb in the half hour I spent looking at it.  Once again airliners disturbed the view.

Wednesday, March 16, 2016

astrometric calibration

We're in for a spell of clear weather for the next several days, so last night I finally started my double star astrometry adventure.  While having the 12.5-inch on a permanent backyard installation on a driven mount (in my case an equatorial platform) is a major benefit of building the roll off shed last year, doing double star astrometry was the primary force to drive me into the effort.  I have modest hopes: it's for my personal challenge, not necessarily for publication.  Last night proved it would be a challenge indeed.

I put my astrometric eyepiece in a 3x barlow and pointed the scope to Sirius to get the finders aligned, and of course to give "first light" of the assemblage to the Pup.  And there is was, pretty widely separated in the field (531x, 0.6 exit pupil, and 0.08° TFOV – can that be right?).  Seeing was variable and since I was viewing after full darkness the diffraction was much larger.

I then turned to Iota Cancri to take some separation measures.  It's a lovely orange and blue pair; I resolved airy disks but the surrounding diffraction rings were quite bright -- perhaps a sign of the mirror's overcorrection?  The need for a solid mount with very fine controls became immediately apparent.  I could not center the stars in the center scale of the eyepiece; the Zlomotion apparatus I bought last year moves the stars too far in the field and the mount has a jerky motion which then wobbles for several seconds.  And this when there was no wind whatsoever.  I had to let the stars drift into the center scale -- meaning the equatorial platform is not tracking so very precisely.  With patience I was able to collect the needed 10 observations to make an initial calibration for this and also Beta Monocerotis, a triple with nearly equally bright white stars. 

I will consider what to do to reduce the wobble.  I know my central pivot is somehow not tight enough.  And I think my altitude bearings are too small.  For certain the tube is not balanced with relation to the mount.  Fixing these will probably help, but not fully solve the problem -- I'd need better tracking and better slow motion controls, for which I may need to resort to electronics.  But I'll give this some time (I can't afford to spend more on this right now).  Patience and perseverance will prevail.  Aside from doing this as a home project, I'm interested to try this set-up on the 30-inch Challenger telescope -- we'll see how steady that mount is!

I tried Sigma Orionis to see whether I could get the AB split, but not -- Orion is well past meridian.  A sheet of thin marine layer was moving in, so transparency was hurt, but seeing was still good.  I had a long stare at the moon at 553x, so much detail.  At some point I'll spend more time to learn the names of all these features.  Jupiter was overall soft at 340x but there were waves of good seeing every 7-8 seconds where cresting waves of festoons in one of the equatorial bands became clear, along with nearby large oval spots -- one of them could have been the GRS but it lacked color.  Strange how the seeing was so predictable like that.  At one point an airliner on the landing path to Oakland airport passed by near to Jupiter, and the ripples from its jet exhaust disturbed the view. 

Monday, March 14, 2016

brief jupiter double shadow

This evening from about 7:30pm to 9:30pm there was to be a double shadow transit of Jupiter, Io and Europa.  I opened up the shed upon arriving home from work, and went out after eating dinner at 7:30.  It was still twilight so I collimated and pointed to Sirius to get the finders aligned -- and wouldn't you know the Pup, Sirius B, was easily visible.  The seeing was not particularly good, and the transparency was awful.  I suspect because it was still twilight out Sirius itself did not shine so "brightly" so the Pup was outside the usual diffraction mess.  I tried this trick with Antares last year, trying to see its B star in the twilight, but no such luck that time. 

Jupiter was too low and I needed to run an errand.  I came back at around 8:40pm and Jupiter still had not cleared the neighbor's roof from where the 12.5-inch stood.  And there were clouds moving in from the west, fast.  I dashed to set-up the 8-inch, and was just able to catch the event.  I saw the two shadows at 180x nearly on top of each other; one (Io's) was obviously larger than the other.  I had Val take a look; it took a couple of minutes but she saw it too.  When I looked again the shadows had merged, it appeared -- but the view was very soft so it could have been tube currents or the high clouds ruining the view.  Coming outside a little while later, the sky was lost to cloud.

It will be clear for the next couple of days, so hoping for more viewing soon.

Sunday, March 13, 2016

telescope maintenance...

It's been cloudy and rainy the last few days, but I've not been idle.  Last night I went up to Fremont Peak where Ron Dammonn showed me how to use the Challenger 30-inch telescope.  It's big!  It will be a handful to move and manage, but I am looking forward to the views.  Next chance I have I'll give it a go.

Today I made an eyepiece holding shelf for my home observatory, somewhere to stow my astrometric eyepiece and other accessories.  And almost on a whim I decided to clean the mirror on the 20-inch, which turns out really needed it.  It cleaned up nicely.  I put on a new center spot and corrected some problems with the sling in the cell.  It should be good to go the next opportunity, which sadly might not be for another could of weeks.

Tuesday, March 1, 2016

bino session

Some clear skies this evening, so spent some time with the big binoculars, checking Orion's sword, M45, M41, and the star fields of Monoceros.  The Hyades are very lovely.  I was picking out colored, mostly orange and red, stars -- doing the AL Carbon star list has made me more attentive, if not more sensitive, to star colors, and it's very pleasing.

After a half hour clouds moved through, and from what I could see of the west, more was coming.  But wouldn't you know it, after I packed the big binoculars away it was clear enough.  I have a bad habit of ending sessions too early.  Seeing was good too; Sirius hardly flickered.  It would have been a good night for doubles.

I used my 8x56 binoculars for a while, sitting in a lounge chair, taking it all in.  M38-M36-M37-M35 form a chain of star clusters which are really not very far from each other, all within the same or just beyond the same FOV.  It was nice to have the wider perspective.  

Some stormy weather coming, so hope to finally put together my astrometric eyepiece set-up for double star observing, so I'm ready to go when it clears.