The Head of Orion

 Lambda Orionis, or Meissa, is the brightest star in a sparse open cluster that forms the head of Orion.  The star and its associated cluster, known as CR 69 (Collinder 69), forms a triangle with the two shoulder stars Betelgeuse and Bellatrix.

credit: SkySafariAstronomy.com

Meissa (center).  Tokina 400mm f/5.6 SD + Metabones 0.71x reducer. ISO 1600, 30 s

Seestar S50.  2 min.

Meissa is a visual double star that makes a good target for small telescopes.  The two components are magnitudes 3.4 and 5.5 and are separated by 4.4 arcsec.

Meissa A+B.  Celestron C6 + 2.5x Powermate.  Stack of 3 images, ISO 800,  0.5 s.

Capturing an image of the GAIA spacecraft

 The GAIA (Global Astrometric Interferometer for Astrophysics) spacecraft is a European Space Agency (ESA) instrument launched in 2013.  It employs the largest digital camera ever deployed in space (952 MP) and has mapped the positions of over two billion (10⁹) stars with unprecedented precision during its operational life.  Due to dwindling fuel supplies, the science mission was ended on 15 January.  The spacecraft is now undergoing testing and calibrating before it is sent into a graveyard orbit around the sun.

The GAIA spacecraft has resided in an orbit around the L2 Lagrange point, which is a semi-stable location on a line opposite the sun from earth, approximately 1.44 million km (899,000 mi) distant. The spacecraft is normally too faint to be seen from earth except by the largest telescopes.  During this decommissioning phase it has been reoriented with respect to the sun and the brightness is predicted to increase to around magnitude 15.  This is within range of amateur telescopes.

Under the dark sky in Creede I can routinely capture magnitude-15+ asteroids with a 135mm f/2 telephoto lens and 30–60 sec exposures.  That is more difficult with the brighter sky in urban Santa Fe, so this was a good opportunity to test the long-exposure capability of the 250-mm focal length Seestar S50.

GAIA's orbit has recently taken it within a few degrees of the star cluster M67 in the constellation Cancer. This was a good starting point for star hopping to the predicted spacecraft location.  The Seestar app currently has no way to directly enter celestial coordinates, so it was necessary to manually point the scope using the associated SkyAtlas app.

M67, the Golden Eye Cluster.  2 min.

I used a 15-min exposure to capture GAIA.  The centering is off because of the manual positioning and guessing, but it worked:  an image of a spacecraft nearly a million miles away!

GAIA is circled.  cropped from the original image.  11 pm MST 27 Jan.

Here is a finder chart showing the predicted position.  This was generated using the GAIA Ephemeris Service of the ESA.  This shows the expected position in 15-min intervals as seen from Albuquerque, which is the nearest predefined location.  Relative to these positions, there is a parallax of about 0.24 arcmin as seen from Santa Fe.  This finder chart represents just a small section of the above image.

This next image is a chart generated by Stellarium with the predicted position marked by the crossed circle (parallax not accounted for):

Finally, an expanded crop from the Seestar image (about 15 arcmin square) with some stars labeled with the magnitudes pulled from Stellarium.  

Wider views with the Seestar S50

 The IMX462 imaging chip used with the Seestar S50 limits the field of view to 1.27° x 0.71°.  ZWO has included in their Seestar imaging app an automatic mosaic creation tool called "framing" that can double or triple the single-shot field of view.  

I tried the framing mode with two subjects that are a little too wide for a single-shot exposure:  the Double Cluster in Perseus, and the galaxy pair called Bode's Nebulae (M81 and M82) in Ursa Major.   This mode works remarkably well.  The biggest drawback is that it requires considerable time to complete.  The two examples shown here each took 20 minutes before the exposure was ended.  The field-of-view expansion factors were 1.4x and 1.5x.

M82 (left) and M81 (right).  Cropped from the original 1.4x mosaic.

Both of these galaxies were previously captured with the Seestar S50, but are too widely separated to fit into a single frame.  The framing mode nicely captures both at the same time.

The Double Cluster: NGC 869 (bottom) and NGC 884 (top). Cropped from the 1.5x mosaic.

In spite of what I consider to be a long acquisition time, the advantage of the Seestar is that I was seated comfortably in the warm house monitoring the progress on my iPad while these automated exposures ran to completion.

Here is a finder chart showing the location of the two galaxies (Bode's Nebulae) relative to the Big Dipper and Polaris:

credit: SkySafariAstronomy.com

More comfy indoor observing with the Seestar S50

 Another clear night provided an opportunity to try out the cross-star "filter" with the Seestar S50.  This filter consists of two rigid crossed wires.  It is meant to simulate the diffraction spikes caused by secondary-mirror holders in Newtonian and Cassegrain telescope designs.  It is purely an aesthetic effect.

The Cross-Star filter and lens shade are add-on accessories by Omegon.

NGC 457, the Owl Cluster, in Cassiopeia. 2 min.

Cluster NGC 188 in Cepheus. 8 min.

The open cluster NGC 188 is within the boundary of the constellation Cepheus, but it is only 4 deg from Polaris in the northern sky.  It is a dim cluster that is one of the oldest of its type in our galaxy.

Cluster M52 in Cassiopeia.  5 min.

Galaxy M82, the Cigar Galaxy, in Ursa Major. 5 min.

Bellatrix.  1 min.

Bellatrix is the third brightest star in the constellation Orion.  It is on the right shoulder directly across from red Betelgeuse.

Armchair observing with the SeeStar S50

 A clear sky but cold termperature was good motivation for trying out the ZWO SeeStar S50, which has been sitting idle since the return to Santa Fe.  The SeeStar is an automated imaging telescope that can be controlled via Bluetooth or wifi with an app on a phone or tablet.  The telescope objective is a 50mm f/5 apochromatic triplet and the imaging chip is a Sony IMX462.  The chip has 2.9-micron pixels in a 1920 x 1080 array.  The field of view is 1.27 deg x 0.71 deg.

The unit was leveled on its tripod in the house, then carried outside and deposited on the concrete patio.  After powering up the scope, I retreated to the warmth of the house and settled into a comfy armchair to begin the observing session.  

The following images were post-processed from the internally-stored FITS files rather than the JPEG files that are transferred to the iPad.  Both file types are automatic stacks of 10-sec sub exposures.  All imaging parameters were the default settings. 

The measured sky brightness was sqml=19.72 mpsas to the north and 19.43 to the south.

M1, the Crab Nebula in Taurus. 5 min.

M35 in Gemini. 2 min.

M36, the Pinwheel Cluster in Auriga. 3 min.

M37 in Auriga. 3 min.

M38, the Starfish Cluster, in Auriga. 3 min.

M42, the Orion Nebula.  5 min.

M45, the Pleiades. 3 min.

Galaxy M81 (Bode's Nebula) in Ursa Major. 8 min.

The Horse Head Nebula (IC 434) in Orion.  8 min.

NGC 7789, Caroline's Rose, in Cassiopeia. 5 min.

NGC 457, the Owl Cluster in Cassiopeia. 2 min.

NGC 869 and 884, the Double Cluster, in Perseus. 2 min.

SeeStar S50. The lens shade is an add-on accessory by Omegon.

Six planets

 Aside from the moon, the four brightest objects in the night sky right now are:

1. Venus, mag -4.5
2. Jupiter, mag -2.4
3. Sirius, mag -1.4
4. Mars, mag -1.3,

and they are all visible at the same time in the evening sky.  In addition to the three bright planets in this list, three more are also visible.  Saturn, at mag 1.1 is easy to see only 2.2 deg from Venus. Uranus is almost directly overhead.  At mag 5.7 it is theoretically visible to the unaided eye, if you have young eyes and are in a dark-sky location.  It is easy to see with binoculars.  Neptune is in the western sky with Venus and Saturn.  At mag 7.9 it requires big binoculars (e.g. 7x50 or larger) and the end of twilight.

Neptune, Saturn, Venus.  Sigma 30mm f/1.4 @ f/1.6 + softon filter. ISO 800, 10 s.

Neptune.  Olympus 75mm f/1.8 @ f/2.5.  ISO 800, 10 s.

Saturn and Venus.  Olympus 75mm f/1.8 @ f/2.0. ISO 800, 6 s.

Jupiter, the Hyades, the Pleiades, and Uranus.  Sigma 30mm f/1.6. ISO 800, 10 s.

The Pleiades and Uranus.

Castor, Pollux, and Mars lined up.  Sigma 30mm.  ISO 800, 15 s.

Castor, Alpha Geminorum, is an attractive double star for small telescopes.  The two components are currently separated by about 5.5 arcsec and orbit their common center with a period of 459 years [Guillermo Torres et al 2022 ApJ 941 8].  Each star is also a spectroscopic binary, making this a quadruple-star system.

Castor A + B.  Sky-Watcher SkyMax 102 MCT+ E-M5iii + Tele Vue 2.5x powermate.  Stack of two images: ISO 200, 1/2 s + ISO 400 1/3 s.

There is also a third fainter visual component, Castor C (not seen here), which is itself a spectroscopic binary.  Castor is therefore, in total, a six-star system.

Orion is always an irresistible photographic target.

Neptune, Saturn, Venus,  Sigma 30mm, no filter.

Bright planets. New telescope.

 There are three bright planets in the evening sky.  Venus is hard to miss at magnitude -4.5 in the western sky at dusk.  Jupiter is high in the sky at magnitude -2.6.  Late in the evening Mars climbs higher in the east at magnitude -1.4.  Saturn is still visible only about 2.6 deg from Saturn, but at magnitude 1.1 it is 174 times fainter.

Jupiter and the Hyades.  Nikon 85mm f/2 Ai-S, ISO 800, 20 s, softon filter.

Mars lined up with Castor and Pollux.  Nikon 85mm f/2 Ai-S, softon filter.

The sky brightness prior to moonrise was typical for Santa Fe, sqml = 19.68.

The new telescope is a GSO 4.5 inch (114 mm) classical Cassegrain, nominally f/12.  Star-field and moon images from the last two nights give an actual focal  length of 1427 mm, which puts it at f/12.5.

Unlike commercial Schmidt-Cassegrain (SCT) and Maksutov-Cassegrain (MCT) telescopes, a classical Cassegrain telescope has fixed mirrors and a fixed focal plane (at infinity focus).  Achieving  focus with an eyepiece or camera therefore requires a proper combination of spacers and drawtube adjustments.  This particular scope has a light-weight carbon-fiber tube and the center of gravity is at the rear where the primary mirror and focuser are located.   An extra dovetail was added so that the scope could be moved forward far enough on the mount to obtain proper balance.

GSO 4.5-inch classical Cassegrain, set up for imaging.

I don't yet have a correct-size Bahtinov mask for precise focusing, so for the following images I had to wing it by looking at the camera monitor and trying to judge position of best focus.  Additionally, the CG-4 mount is not polar-aligned well enough for long exposures, so they were kept short.  It is also worth noting that this mount has no GO-TO functionality, so objects must be found the old-fashioned way by star-hopping with a finder scope. This can be a challenge under Santa Fe's bright sky.

M35 in Gemini.  Sony A7iii, ISO 1600, 15 s.

NGC 457, the "Owl Cluster" in Cassiopeia. Sony A7iii, ISO 1600, 15 s.

One nice thing about this scope is that it illuminates a "full-frame" sensor (36 mm x 24 mm) with no obvious vignetting.  I haven't used it enough to draw conclusions about edge-of-field aberrations. The above images were binned by 4 to hide the imprecise focusing blur.

 

The Owl Cluster again.  E-M5iii (micro four thirds).  ISO 1600, 15 s.

Mizar (top) and Alcor (bottom). E-M5iii. ISO 800, 1 s.

The Mizar and Alcor pair form a naked-eye double star in the handle of the Big Dipper.  Mizar itself is a visual double star in a telescope.  Each of the two components seen here is also a spectroscopic double, which makes Mizar a quadruple-star system.

The 18.1-d moon.  E-M5iii, ISO 400, 1/160 s.

Moon. Polaris. Sky-Watcher SkyMax 102 MCT.

 The 11.8-day moon was only three days past perigee on Friday night and therefore slightly larger (32.45 arcmin) than average.  I used this angular size to measure some effective focal lengths for a Sky-Watcher SkyMax 102 MCT (Maksutov-Cassegrain telescope).  Like the previously discussed Celestron C6, this scope focuses by changing the mirror spacing, which moves the focal plane and changes the focal length. The nominal focal length is 1300 mm, which corresponds to a focal ratio of 12.75, but that is true for only one specific location of the focal plane.

An Olympus E-M5 camera with T-adapter was used to image the moon directly inserted into a SCT-2" adapter and then inserted into a 2" diagonal.  When inserted directly into the SCT adapter, the camera image sensor was 88 mm from the base of the scope and yielded a focal length of 1290 mm.  At this focal length the moon image just fits onto the micro-four-thirds sensor.

 

A 2-inch mirror diagonal plus 5-mm parfocal ring adds 110.5 mm to the back-focus position.  The measured focal length for this configuration was 1671 mm.  The entire moon no longer fits onto the sensor.

From these two measurements the focal-length differential was determined to be 3.45-mm focal length per mm of extension.  This gives a focal length 1526 mm at the exit flange of the 2-inch diagonal, for a focal ratio of f/15.  This result is useful for estimating the magnification provided by an eyepiece when used for visual observing.

With the moon measurements completed, the scope was turned toward Polaris in the straight-through (1290 mm FL) configuration, this time with an E-M5iii.  The "North Star", Polaris, lies about 2/3-deg from the north celestial pole.  Polaris is actually a triple-star system.  The magnitude-2 primary Polaris A is a spectroscopic double star.  Polaris B, a 9.1-magnitude companion star, is separated by 18 arcsec.   This visual pair is a challenge for small telescopes because of the large magnitude difference.

Polaris A and B.  E-M5iii, ISO 1600, 1 sec.

The star colors are usually described as yellow(ish) for Polaris A and white for the fainter Polaris B.  However, in Burnham's Celestial Handbook, Vol. Three, (Dover, 1978) p.2009, Polaris B is described as "a small companion which seems of a pale bluish tint."

Straight-through configuration.

With a 2-inch mirror diagonal added.

Configured for visual observing

Added the following day (11 Jan):

E-M1iii. ISO 800, 1/640 s. (binned x 2)

 A 1:1 crop of the southern quadrant:

Another shot of Polaris (looks a little bit cleaner than the previous):