29 December 2015

A Deep-Sky Planer user asked me to create observing plans for objects in the Small Magellanic Cloud (SMC). The data came from 5 catalogs revised by Mati Morel of New South Wales, Australia. I contacted Mr. Morel about the project, and he kindly gave permission for me to use his work. He also sent me the latest updates to his data.

Small Magellanic Cloud. Credit: NASA/CXC/JPL-Caltech/STScI
The data in this series of plans are contained in 5 lists compiled from examining the Hodge & Wright atlas of the SMC (1977). Mr. Morel examined the atlas and consulted various sources for position, magnitude and size information for each object. He also included comments on many objects. I have used the latest published data from SIMBAD for position, magnitude and size. There appears to be little difference between the two sets of data, except that magnitude information is somewhat different. There is photometric data available for most objects in multiple bands. The band used for the magnitude data for each object in the plans is indicated. Magnitude data in the V band is preferred where available. I believe this is more useful to visual observers.

Together, the 5 plans contain 405 objects. Some entries are duplicated among the catalogs, but together these represent a thorough coverage of nebulae and clusters in the Small Magellanic Cloud.

The plans in the Deep-Sky Planner Plan Library are named:
  • SMC Henize nebulae
  • SMC Hodge Wright clusters
  • SMC Kron clusters
  • SMC Lindsay clusters
  • SMC Westerlund Glaspey clusters

  1. Morel's comments are maintained in the User text column. These are essential to his work.
  2. Object types in DSP are not as narrowly defined as those in SIMBAD. For example, 'Open Cluster' is assigned in Deep-Sky Planner to object types 'cluster of stars', 'star association and the like in SIMBAD.
  3. Lindsay's paper is crucial to understanding the clusters in the SMC. You can read it here.
  4. Lindsay 106 and 109 are mislabeled on the Hodge & Wright (1977) atlas of the SMC

10 December 2015

Adventures with Sky Commander

I have used a Sky Commander digital setting circle computer with my telescopes since 1991. I can thank Tom Clark from Tectron Telescopes for turning me on to this wonderful gadget. I wouldn't be without it.

My first Sky Commander started out on a 20" Dob and later moved to a 14.5" Dob. I also added encoders to a 8" Dob so that I could use the Sky Commander with it. I have been running my Sky Commander on both the 14.5" and the 8" for years.

I recently got a new Sky Commander XP4 to use on the 14.5" so that I can permanently assign the older one to the 8". The configuration is a little different on the two scopes, so having one Sky Commander for each scope is helpful.

Old and new Sky Commanders

A feature was added to Deep-Sky Planner 6 that allowed users to upload an observing plan to the Sky Commander in its special objects list (entries 0-58). I have used this feature to upload coordinates for comets, asteroids and deep-sky objects that weren't in the Sky Commander database.

While testing Deep-Sky Planner with the new Sky Commander, I found that I still had to upload plans when the Sky Commander was at the Set Date prompt. That requirement never seemed right to me because I didn't see it documented anywhere.

I contacted Sky Engineering about this and we found that a firmware change would cure the problem. After some back and forth and some testing, a new firmware version emerged. I flashed the new firmware into the XP4 and the problem was solved!

Going forward, Deep-Sky Planner users with a Sky Commander having firmware prior to version 5.03 SP02 will need to upload plans when Sky Commander is at the Set Date prompt. Users that are able to update the firmware to version 5.03 SP02 or later should be able to upload plans to Sky Commander when it is at the Set Date prompt or in its normal operating mode. This is an added convenience that will make using Sky Commander with Deep-Sky Planner a little smoother.

I'd like to thank Victor McKeighan at Sky Engineering for his kind help in resolving this issue.

08 September 2015

More Southern Observing

Another observing plan of special interest to visual observers and astrophotographers with access to southern skies has been posted to the Deep-Sky Planner Plan Library. The plan is called "Sandqvist Lindroos Dark Nebulae".

The plan includes the 42 objects identified by two astronomers working at the Stockholm Observatory in their 1976 paper about dark dust clouds in the southern sky. Sandqvist and Lindroos examined  Palomar Observatory Sky Survey plates for dark clouds in previously unexplored declinations (-32° to -46°). They researched the presence of formaldehyde in the nebulae that they identified. As part of their process of identifying these dark clouds, they cataloged the area and opacity of each cloud in the survey - data which appear in the observing plan mentioned above. Objects in the plan also include their corresponding Barnard numbers where appropriate.

Observing these objects will require dark skies and large aperture. Imaging these objects should offer some interesting results since these objects are not imaged frequently.

27 July 2015

Southern Hemisphere Observing

An observing plan called "RASC Southern Splendours" was posted recently to the Deep-Sky Planner Plan Library. The plan is based on an article of the same name from the "Observer's Handbook 2013" by the Royal Astronomical Society of Canada. The plan contains 75 showpiece objects that are visible to southern hemisphere observers. The most northerly object in the list is M 83 at -29° declination; the most southerly are at -72° (there are several, including the Small Magellanic Cloud).

Small Magellanic Cloud
Image credit: NASA/CXC/JPL-Caltech/STScI

We northern hemisphere observers often lament the great observing targets that are enjoyed by our southern hemisphere counterparts but not visible to us. I've read recently of the ongoing show displayed by comet C/2014 Q1 (PANSTARRS), and I admit to some envy.

While southern observers can enjoy the "Splendours" plan anytime, we northerners can make the trek south to enjoy it too. Such is the case with a small group of long time friends who are headed to the 2016 OzSky Star Safari in April. Unfortunately, those dates collide with the Northeast Astronomy Forum (NEAF) for me, but that's another story.

I look forward to hearing about the observing at OzSky, and I look forward to making the trip myself in the future. Whether you live in the southern hemisphere or not, the "Splendours" plan is available to all Deep-Sky Planner users now, and I hope observers north and south find an opportunity to use it.

16 June 2015

Observing & Imaging Dark Nebulae

Observing and imaging dark nebula is an interesting deviation for most amateur astronomers as we are trying to detect the absence of light - just the opposite of our normal pursuit. Dark nebulae are clouds of dust that obscure light from objects behind them. We have known about dark nebulae for quite some time, but they still remain somewhat enigmatic.

Both America's Astronomical League (AL) and Canada's Royal Astronomical Society (RASC) have observing programs for Dark Nebulae, and each plan is available in the Deep-Sky Planner Plan Library. Each program has very helpful information available to help with observing. See https://www.astroleague.org/al/obsclubs/DarkNebulaeClub if you are pursuing the AL program, or the RASC Observer's Handbook if you are pursuing the Canadian one.

The objects in these plans typically come from E.E. Barnard's photographic survey of dark nebulae (1927), or from B.T. Lynds' more recent survey (1962) based on the Palomar Observatory Sky Atlas images. These catalogs list size estimates, and the Lynds catalog includes a ranking of darkness - again note that magnitude data are not applicable!

Horsehead Nebula
T.A.Rector (NOAO/AURA/NSF) and Hubble Heritage Team

This is a particularly favorable time of year to observe dark nebulae as many lie along the northern hemisphere's summer Milky Way. Although many lie in the summer sky, dark nebulae are visible throughout the year. For example, B 33/LDN 1630 - the Horsehead Nebula - is visible in northern hemisphere's winter evenings. To observe dark nebulae successfully, you need a very dark sky and very well dark-adapted eyes. Some objects can be observed with binoculars, but most require a telescope. The Great Rift in Cygnus and Aquila can be observed with the unaided eye.

Observing dark nebulae can be a nice change of pace from observing bright nebulae, galaxies and clusters. Why not give them a try using one of the observing plans available from the Plan Library?

21 April 2015

What Was Old Is New Again

November 1965 Sky & Telescope
Recently I had the pleasure of hearing Jim Mullaney speak at the Southern Star Astronomical Convention in North Carolina. Jim is a prolific author and longtime contributor to Sky & Telescope magazine. In one of his talks, Jim mentioned a series of articles that he and Wallace McCall wrote years ago called 'The Finest Deep-Sky Objects'. The articles were published in 3 issues of Sky & Telescope spanning November 1965 through January 1966.

The objects selected for the articles met the simple criteria that they had to be bright enough and the correct size to be impressive when viewed through telescopes of various apertures from the latitude of the Allegheny Observatory in Pittsburgh, Pennsylvania. The list encompassed 105 objects that were popular on public observing nights over a 5 year period.

The articles are important even 50 years later because visual impressions of the authors are included - information quite useful to any observer. While the list is a wonderful guide for novice observers, it is also a very useful list for any observer preparing for a public observing session. While over half the objects included are double stars, there are excellent examples of all types of objects in the lists.

The objects listed in the articles are now available as an observing plan file for Deep-Sky Planner. It can be downloaded by licensed users from the Plan Library. The plan contains 119 objects because several of the objects in Mullaney & McCall's lists are multiple star systems; Deep-Sky Planner lists multiple pairs of stars in these cases.

These lists remain a timeless guide for astronomical observers with telescopes of moderate sizes.

09 March 2015

Introducing The Herschel Sprint

Mark Bratton, author of The Complete Guide to the Herschel Objects, wrote a fascinating piece in the April issue of Sky & Telescope that describes a very productive night of observing by William and Caroline Herschel in April 1785. Entitled "William Herschel's Extraordinary Night of Discovery", the article describes how the Herschels conducted observations of 74 objects in a single night. The article includes comments about each object, making it a highly recommended read. Once you've read the article, it feels like you've observed with William and Caroline - a very neat thought.

This season of the year has it's Messier Marathon, but if you've mastered that, the 'Herschel Sprint' offers a similar but greater challenge. The Sprint is a very inviting and historically interesting project for modern observers with 15 inch or larger telescopes. (The Herschels accomplished their feat with an 18 inch speculum metal reflector.) You can read more about the Herschel Sprint from Sky & Telescope editor Susan Johnson-Roehr. Licensed users of Deep-Sky Planner can download the Herschel Sprint observing plan from the online Plan Library now. The plan contains all 74 objects from the article along with modern object data.

The Herschel Sprint Observing Plan
Pursuing the Herschel Sprint with Deep-Sky Planner gives the modern observer many advantages - GoTo telescope slewing, managed object images, inter-operation with planetarium software and automated logging. One can only imagine what William and Caroline might have done with GoTo and automated logging!

Knightware thanks Sky & Telescope magazine for granting permission to use data from this special article to create an observing plan for Deep-Sky Planner users.

24 February 2015

Arakelian Galaxies

An observing plan containing the Arakelian Galaxies has been posted recently to the Deep-Sky Planner Observing Plan Library (licensed users only.) This plan should be of particular interest to galaxy hunters, so more background is included here.

Russian astrophysicist Marat Arakelian published a paper in 1975 in which he studied the correlation between high surface brightness (HSB) galaxies and active galactic nuclei. Arakelian defined HSB as 22 magnitudes per square arc second (mpsas) or brighter.

Deep-Sky Planner shows surface brightness (SB) for galaxies when possible. The value comes either from catalogs when it is available, or it is calculated using a formula that is a little different from that used by Arakalian. Because of these differences, the plan has some SB values that are dimmer than 22. Most of the galaxies in the plan are smaller than 1 arc minute in size, thus contributing to high surface brightness. With this in mind, the observing plan contains about 500 of 591 galaxies with SB values of 22 or brighter. These galaxies (with SB <= 22) should be bright enough to be seen in large amateur telescopes in a dark sky location - those with skies perhaps 20.5 mpsas or darker.

Arakelian studied galaxies no further south than -3 degrees declination, so they are visible to northern hemisphere observers, and most are visible to observers at moderately southern latitudes.

The study found that there were more elliptical and lenticular galaxies in the study sample than one might find in a random sample, thus proving that there was a correlation between high surface brightness and active galactic nuclei. Arakelian's study was an important basis for further research. Arakelian himself had only a few years to explore the matter further since he died in 1983 at the young age of 52.

05 February 2015

Integrated Flux Nebulae

I recently read about integrated flux nebulae (IFN), whose name was coined by amateur astronomer Steve Mandel. Steve photographed and cataloged a number of objects at high galactic latitudes that were wispy, dusty nebulae, though uncatalogued by professional astronomers.

A quick visit to Steve's web site reveals his personal pursuit of identifying these objects, and what his research has uncovered about them. Steve's work on these objects has been recognized by the American Astronomical Society (2008 Chambliss Award for Amateur Achievement) and the Astronomical Society of the Pacific (2008 Amateur Achievement Award). Professional astronomers have begun investigating these objects based on Steve's work.

In a recent email from Steve, he explains that the catalog will be renamed "Mandel Catalogue of Unexplored High-Latitude Galactic Dust Nebula". He continues his work on this project.

An observing plan containing the current list of integrated flux nebulae has been uploaded to the Plan Library which is available to licensed users of Deep-Sky Planner. It contains the list of objects and Steve's comments about each. Steve has kindly granted permission to use this information in Deep-Sky Planner.

31 January 2015

Wide-Field Observing

I recently posted an observing plan to the Deep-Sky Planner Plan Library  containing most of the objects that appear in the "Wide-Field Wonders" article in the 2013 RASC Observer's Handbook. (The article also appears in the 2015 edition.) While most of the objects are nebulae and clusters, a few are more esoteric objects that aren't found in typical catalogs - things like molecular clouds. This plan contains an excellent variety of imaging and viewing targets, so I encourage readers to check out the article to get background information.

Observer's Handbook from
Royal Astronomical Society Canada

Wide-field observing (both visual and imaging) generally requires a rich-field telescope, binoculars, or a fairly fast telescope with a long focal length eyepiece. These objects often have low surface brightness, so a dark location is definitely indicated.

Wide-field observing can be a nice change of pace if your usual deep-sky observing includes galaxies, planetary nebulae and such. For example, I've observed the Veil Nebula in Cygnus dozens of times with various telescopes. I always enjoy viewing it with a UHC filter and magnification around 100x. The telescope I use most often these days is a 14.5" f/4.5 reflector. My rather ancient 20mm Nagler eyepiece produces magnification of 96x with a field of view of about .86° with this telescope. I've used this combination of equipment for several years, so the end result is somewhat expected.

14.5" f/4.5 Reflector

I got a new lower power eyepiece a year or so ago that was a game-changer on things like the Veil. The new eyepiece is a 31mm Nagler which produces 61x with FoV of 1.3°. It turns out that the view with the 31mm eyepiece allows me to see most of the nebula at once. The view with the 20mm requires a lot of scanning around to view the entire nebula. While the detail is much greater with the 96x view, the ability to 'get it all' at 61x is a welcome new capability. I've also observed the Veil through a friend's Tele Vue-NP101 (101mm, f/5.4) with a 31mm Nagler. The view was stunning and quite different from my usual result. That view really inspired the purchase of the 31mm eyepiece.

TeleVue's 31mm Nagler

From this I think it is fair to suggest that we get into familiar patterns with our observing - both imaging and visual. A simple change like using a different eyepiece can produce a very different view, even with an object that is very familiar. Perhaps we should take the next step with this by pursuing an observing plan that includes objects well off of our beaten path. The "Wide-Field Wonders" plan may be such a refreshing change of fare.

01 January 2015

Robert Trumpler's Open Clusters

An observing plan called the Trumpler Clusters was created recently for Deep-Sky Planner and posted to the Plan Library. Licensed users can view and download the plan by logging into the Deep-Sky Planner Community and browsing for the plan in the Library (Help | Community Page).

Open clusters are wonderful observing targets during the present season. Some of the Trumpler clusters are a bit dim for common binoculars, but a telescope serves well when observing them. The Trumpler clusters are located between declinations +63 and -63, so many are visible to both northern and southern hemisphere observers.

I have looked for Robert Trumpler's original paper for years without finding it. Phil Harrington's recent article on Cloudy Nights included a link to Trumpler's original paper which is available on ADS at Harvard. (Thanks go to Phil for providing this!)

Trumpler 36 / IC 1311
© 1995 by the Association of Universities for Research in Astronomy, Inc
Trumpler's paper was published in 1930 and sought to define all known open clusters. Thirty-seven of the objects in the list were unknown when the paper was written, and these have become known as the Trumpler clusters. All but Trumpler 36 are still recognized in today's literature. Trumpler 36 is a bit of a riddle, although it seems to be IC 1311. Trumpler's paper also included a study of cluster diameter, distance and magnitude of member stars. It's a very interesting paper to read even some 85 years later. Any dedicated observer of open clusters should have a look at it.

The observing plan that appears in the Deep-Sky Planner library includes updated coordinates and size information from "Optically Visible Open Clusters Catalog" (Dias+, 2002-2012). Trumpler's original classifications are also included in the plan. The well-known Trumpler classification system encodes concentration, richness and brightness as follows:

I=detached cluster, strong concentration
II=detached cluster, little concentration
III=detached cluster, no concentration
IV=undetached cluster

1=equal brightness
2=medium range of brightness
3=bright & faint members

p=poor, < 50 members
m=moderate, 50-100 members
r=rich, > 100 members

Enjoy observing the Trumpler Clusters in the new year!