Posts Tagged ‘np101’

M31 – The Andromeda Galaxy

November 14, 2012 Leave a comment

After taking the luminance exposures that were intended to be a test for the new STL-11000M, I couldn’t help but dig up some old DSLR exposures of M31 and merge their color data into the image.
This is 18×10 min luminance with an SBIG STL -11000M through an NP-101 at the native f/5.3 combined with color data from 169×4 min (11+ hrs!) taken with a Canon 450D through an 80 mm refractor at f/6 last November.


A quick evaluation of the NP-101 for use with the SBIG STL-11000

November 10, 2012 Leave a comment

I recently purchased an SBIG STL-11000, and my biggest concern was whether buying a camera with such a large sensor was going to require me to buy a new telescope to cover that sensor.  My main scope is a Televue NP-101 (the non-is version), which means I have to shoot through the 2″ focuser.  While I’d trade up to the NP101-is or even a Tak FSQ-106 at the right price, let’s face it:  those are very expensive upgrades.

Last night was first light with the new camera, and I’m posting this information to help others make a similar decision.  Two important caveats here:

  1. Focus was a little off.  I think I need to recalibrate FocusMax, and this was just meant to be a “first light” test of the camera. So compare the relative sharpness of the corners, not the overall sharpness.
  2. No polar alignment was done, so there is a little field rotation evident.

First is the question of whether the NP-101 can deliver sharp stars all the way out to the corners.  Let’s have a look at the full image first.

This is 18 10-minute exposures taken through a luminance filter, synthesized in DeepSkyStacker.  When I loaded up the files in Photoshop, it was impressive to see their scale:  4000 pixels across!  Now, let’s look at the corners:

This is sharp enough for me, especially with the field rotation evident.  I am really impressed with the edge performance of the NP-101.  At this point, I’m not seeing a need to upgrade to the FSQ or 101-is.

Second, we have to consider the light fall-off.  I braced myself for considerable vignetting.  Here is the master flat with levels on an 8-bit scale marked in green:

Again, to me this is acceptable performance, though less than ideal.  There is about a third reduction in light at the corners versus the center.  That’s a lot, but it’s not nearly as bad when you move just a little bit inward.  I figure with the usual cropping and overlapping of frames that happens, this won’t be much of an issue.  It’s almost the same levels of vignetting I’ve seen on the ST-8300’s chip when using this scope at f/4.3 via the reducer.  Careful processing there proved that the vignetting wasn’t a problem.

So what’s the verdict?  The NP-101 is perfectly acceptable for use with the STL-11000.  My guess is that the -is version with its larger focuser would perform better, but until I see a deal on one of those, I think I can happily image with this combination.  If anyone has similar information for the STL-11000 with either of the Televue -is scopes or the Tak FSQ scopes, please post a comment for comparison.

IC1396 (most of it) and the Elephant’s Trunk

October 23, 2012 Leave a comment

This is most of the nebula IC1396. IC1396 is huge, about the width of 10 full moons, and it lies in the constellation Cepheus. In astronomical terms, it’s pretty close at only 2000 light years away. The structure in the bottom right is the famous “Elephant’s Trunk,” (vdB 142) which is thought to be an active star-forming region. The largest black dust lane in the middle is Barnard 161.

[ASIDE:  There is a tiny blue blotch directly below Mu Cephei, the big yellow star on the left.  It sticks out like a sore thumb in the O-III images, is visible in the H-alpha images, but it’s absent from the S-II, hence its blue color here.  After a good bit of research, it appears that this semi-anonymous planetery nebula is known as PN G100.4+04.6.  I can find very little else about it other than the basic stats in SIMBAD.  If anyone knows more, let me know.]

As with most of my recent images, this one combines images taken through narrowband filters into a mapped color image where the Sulfur-II emission line is mapped to red, Hydrogen-alpha (+Nitrogen-II) to green, and Oxygen-III to blue.

Image data:

Exposures:  13 x 1200s Ha , 22 x 1200s O-III, 12 x 1200s S-II (15h 40m total)

Software:  guiding by PHD, stacking in DeepSkyStacker

Processing:  Photoshop CS3, modified Hubble palette

Telescope:  Televue NP101 with 0.8x reducer (at about  f/4.3)

Camera:  SBIG ST-8300M with Baader standard narrowband filters, 2×2 binned

Mount:  CGEM

October 17, 20, and 21, 2012

Ced 214 (Sh2-171) and NGC 7822

September 23, 2012 Leave a comment

Cygnus is not the only summer narrowband delight in the northern hemisphere.  Cepheus also hosts some beautiful emission nebulae, two of which are shown here. The object on the left has the lovely name Cederblad 214, also known as Sharpless 171.  The object on the right (that I can’t help but see as a seahorse) is NGC 7822.

Ced 214 is fairly commonly imaged at longer focal lengths to capture its “elephant trunk” pillars of expanding gas, but here I’ve captured a little bit wider of a field at about 430 mm (on the KAF-8300 chip).  If you go even wider, the whole region is covered in nebulosity that when framed properly is known as the Cosmic Question Mark.

This image took five evenings in September to capture.  This object has a low surface brightness, especially in O-III.  This image represents just shy of 20 hours of total exposure time.

Ced 214 (Sh2-171) and NGC 7822

Ced 214 (Sh2-171) and NGC 7822


Image data:

Exposures:  16 x 1200s Ha , 16 x 1200s O-III, 27 x 1200s S-II (19h 40m total)

Software:  guiding by PHD, stacking in DeepSkyStacker

Processing:  Photoshop CS3, modified Hubble palette

Telescope:  Televue NP101 with 0.8x reducer (at about  f/4.3)

Camera:  SBIG ST-8300M with Baader standard narrowband filters, 2×2 binned

Mount:  CGEM

September 9, 10, 11, 12, and 19, 2012

The Western Veil Nebula and Pickering’s Triangle

September 19, 2012 Leave a comment

If Cygnus would stay in the sky all year, I don’t know if I could exhaust all of its imaging possibilities.  This is the Western Veil Nebula, NGC 6960 and Pickering’s Triangle (bottom left). Both are remnants of a supernova from about 5,000 years ago that also includes the beautiful NGC 6888 (not shown) among others.  This nebula is surprisingly bright in all three major narrowband lines, H-alpha, S-II, and O-III, which meant that I could capture a reasonable amount of data in a single night.

NGC 6960 in narrowband

NGC 6960 in narrowband

Image data:

Exposures:  9 x 600s Ha , 10 x 600s O-III, 9 x 600s S-II (6h 40m total), binned 2×2

Software:  guiding by PHD, stacking in DeepSkyStacker

Processing:  Photoshop CS3, tone mapping using modified Hubble palette

Telescope:  Televue NP101 with 0.8x reducer (at about  f/4.3)

Camera:  SBIG ST-8300M with Baader standard narrowband filters

Mount:  CGEM

September 14, 2012

IC443, The Jellyfish Nebula

March 4, 2012 Leave a comment

This galactic jelly isn’t even mentioned in most star atlases, despite being huge (almost a degree across) and easily locatable in the constellation Gemini. It’s probably an extremely difficult visual object, but astroimagers are quite familiar with it because of its distinct shape.  IC443 is a supernova remnant that exploded thousands of years ago, and the filaments you see are the interaction of shock waves from that supernova with surrounding gases.

This is another narrowband image, representing a total of 11 hours of exposures taken over two nights (26-7 Feb).  I’ve used color to emphasize the regions where there is a lot of Hydrogen alpha emission alone (red) from where there is a combination of Oxygen-III and Hydrogen-alpha (green-yellow).

I can’t help but think that the Jellyfish is going to eat the bright star, Eta Geminorium…

The Jellyfish Nebula, IC443

Image data:

Exposures:  25 x 600s Ha, 21 x 600s O-III, 20 x 600s S-II, a total of 11h 0m

Software:  guiding by PHD, stacking in DeepSkyStacker, processing in Photoshop CS3

Telescope:  Televue NP101, 530mm f/5.3

Camera:  SBIG ST-8300M with Baader narrowband filters

Mount:  CGEM

M42 Orion Nebula in Narrowband

February 5, 2012 1 comment

Some weeks, everything goes wrong.

To quench the never-ending thirst for more concentrated photons, I sold my previous scopes so I could trade up to two high-end, fast refractors:  a Borg 77EDII at f/4.3 and a TeleVue NP101 at f/5.3.  I seized rare opportunities to get both used and at great prices.  Only if a Tak FSQ came my way would I have room to improve in the short focal length department.  But with all new scopes come new problems.  The NP101 needed rings to sit on my mount, and an adapter for my stepper motor to control the focuser — $200 and two weeks.  The Borg needed precise spacers to fit my camera, and I’m still working out other kinks — $100 and at least two weeks.

Now I find out that my SBIG’s cooling is not functioning correctly, so basically every piece of imaging equipment I have is “in the shop,” in one way or another.  But sometimes even with adversity, something fun or beautiful slips through.  I took the NP101 out on a hazy, moonlit night because I really wanted to start working with narrowband data.  The obvious, reliable target sat just above my roof:  M42.

The world needs another image of M42 like a hole in the head, but I couldn’t resist.  Before it set, I grabbed two hours of narrowband exposures, and here is my very first narrowband image:

Stats:  SBIG ST8300M, Baader filters, TeleVue NP101 on a CGEM

6x300s H-alpha, 10x300s O-III, 12x300s S-II, 25 flats, NO darks

Stacked in DSS, process in Photoshop CS3.

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