Welcome to Houston Astronomical Society

Founded in 1955, Houston Astronomical Society is an active community of enthusiastic amateur and professional astronomers with over 60 years of history in the Houston area. Through education and outreach, our programs promote science literacy and astronomy awareness. We meet via Zoom the first Friday of each month for the General Membership Meeting and the first Thursday of the month for the Novice Meeting. Membership has a variety of benefits, including access to a secure dark site west of Houston, a telescope loaner program, and much more. Joining is simple; you can sign up online, by mail or in person at a monthly meeting.

July 07, 2022, 7:00PM: Novice Presentation - Via Zoom

"Learn the Lingo: Astronomy From A to Z"

by Debbie Moran

Debbie Moran head shot (2).JPG

Join us on the evening of July 7th for a presentation that will benefit all amateur astronomers. Novice Chairperson Debbie Moran will give a talk entitled, "Learn the Lingo: Astronomy From A to Z". Debbie will go in-depth into astronomical terms that may be unfamiliar, vague or confusing and make them clear and understandable. Many of the terms and concepts she will discuss even seasoned astronomers will find interesting. There is something here for everyone, newbies and veterans alike. And who knows, you might even run across them again. Some of the more obscure terms have been known to pop up in an HAS trivia contest!

July 08, 2022, 6:30PM: July Regular Meeting - IN PERSON and via Zoom

The Lives and Observing Records of William and Caroline Herschel

With Larry Mitchell

ready_to_observe2.jpg

Abstract – In the mid 18th century based on the work of Sir Isaac Newton,  it was thought the universe beyond the solar system was unchanging. William Herschel completely changed this theory, along with many more generally accepted ideas.

Without any formal training he established concepts which persisted for the next 100 years and provided the very foundation of today’s astronomical knowledge. This is why today he is known as the “Father of modern astronomy”. Most people have no idea of the huge database Herschel provided, based solely on his visual observations through instruments he built. These were the finest observations the world had seen, up to that time.

Larry is in possession of every scientific paper William Herschel published and will present information not seen elsewhere. We hope you can attend this very informative presentation.

---------------------------------------------------------------------------------------------------

Our Speaker : We are fortunate to have many accomplished members in HAS and one of them is certainly our own Larry Mitchell.  Larry has been a long time member of HAS. He is strictly a visual ‘Star-hopping‘ observer but admits that he greatly appreciates the work provided by imagers. During his observing carreer, Larry has:

- Observed all 2,508 objects Wm Herschel discovered including the ‘nonexistents’.

-Authored the Mitchell Anonymous  catalog, the MAC which consists of 117,300 previously uncatalogued galaxies. 

-Discovered supernova SN1994S.

- Served as Chairman of visual observing programs for the Texas Star Party and for the Stellafane Convention.

- Owned too many telescopes but mainly uses 36-inch and 20 inch Dobsonians, and a 7 inch refractor.

AP Corner: Let’s Get You Calibrated!

by Don Selle

How to Capture and Process Astro-Photography Calibration Frames

Let me start out by being blunt. If you want to improve the results of your astrophotography or your EAA, you must learn how to take and apply calibration frames to every target frame you take before you align and stack them. This is such an important step that experienced imagers refer to calibrating their sub-frames as pre-processing them. In other words, calibrating your sub-frames is so important that it must be done before any image processing is done.

 

220701_raw-image.jpg
Raw image above – Calibrated image below

Many beginning astro-photographers are either ignorant or ambivalent about taking and applying calibration frames to their hard-won target sub-frames. This is especially true for those of us who set up and take down our imaging rigs (which is most astro-imagers). 

I know this firsthand. Taking and applying darks and bias frames was straightforward for me. I could capture them ahead of time and applying them was easy in any of the astro-image processing apps that I used.

220701km_calibrated.jpg

But flats? That was a different thing all together. It seemed to me that they were difficult to take, adding to my difficulty, I was regularly making changes to my imaging rig, so set up was always a bit of an adventure, 

All Taking flats at evening twilight required being in focus and getting my initial focus required the sky be dark enough that shooting flats was out of the question. 

Dawn flats were also a dodgy option, as I was either taking my rig down and heading back to town before dawn, or (especially in the winter months at the HAS dark site) low clouds or ground fog covered the skies at dawn! 

Fortunately, especially for flats. There are good practices that will help you to efficiently add calibration frames to your imaging workflow and improve your astro-images. But first, a few basics.

Did the Tau Herculids Storm?

by Will Sager

Meteor observers were recently excited about the possibility of an out-of-nowhere meteor shower, called the Tau-Herculids, that offered the possibility of a “storm” at the end of May. Many years ago, my uncle described seeing the 1966 Leonid meteor storm in Virginia and said meteors were falling too fast to count all over the sky. Later I read in Sky and Telescope about observers at Kitt Peak, who got the best display. They witnessed a rain of meteors estimated at 10-40 per second. I have been observing meteors for 45 years and have never seen such a storm. The closest I came to it was the 2001 Leonid shower, when the Earth passed through a rich stream of debris from comet Temple-Tuttle. That night, under dark skies in Arizona, I logged over 1200 over the course of the night. It was awesome, but not quite the storm that my uncle saw. Would the Tau Herculids be my storm?

Meteor showers arise from debris shed by comets or asteroids. The debris expands along the parent body orbit and if the Earth encounters that debris stream in its yearly swing around the Sun, there will be a meteor shower. Owing to perspective, the meteors seem to radiate from a single spot in the sky – like the like the snowflakes when you drive into a snowstorm (Texans will have to take my word on this). The shower is named by the location of this radiant. The Leonids from from Leo, the Perseids from Perseus, and the Tau-Herculids from a point near the star tau-Hercules. Most meteors are tiny grains, dust to sand size, and they cause streaks because they run into the atmosphere at astonishing speeds (more than 50 kilometers per second) and this causes impacted upper atmosphere atoms to be ionized and glow briefly. Every now and then, a larger fragment plows into the atmosphere, causing a bolide (aka fireball), which is an exceptionally bright meteor (usually causing the observer to hoot in delight). The most reliable annual meteor showers have debris all along the parent body orbital path, which happens to intersect the Earth’s orbit. Every year, the Earth runs through the stream, producing the annual shower.

fig2.png

 

 

Find Hercules and His Mighty Globular Clusters

by David Prosper

M92_Hubble-web.jpg

Hercules is one of the standout heroes of Greek mythology, but his namesake constellation can be surprisingly hard to find - despite being one of the largest star patterns in our night skies! Once you find the stars of Hercules, look deeper; barely hidden in the space around his massive limbs and “Keystone” asterism are two beautiful globular star clusters: M13 and M92!  

Since the constellation itself is relatively dim but bordered by brighter constellations, you can find the stars of Hercules by looking between the bright stars Vega and Arcturus. They are fairly easy to identify, and we have tips on how to do so in previous articles. Vega is the brightest star in the constellation Lyra and one of the three stars that make up the Summer Triangle (June 2020: Summer Triangle Corner: Vega). Arcturus is the brightest star in the constellation Boötes, and can be found by “arcing to Arcturus” from the handle of the Big Dipper (May 2021: Virgo’s Galactic Harvest).  You may be able to Hercules’s “Keystone” asterism first; this distinct pattern of four stars is traditionally shown as the torso of the great hero, though some illustrators prefer marking the Keystone as the head of Hercules. What pattern do you see in the stars of Hercules?

Messier Column July 2022

by Jim King

M87-M88-M89-M90.png

Charles Messier, in his active observation life, used several different telescopes.

Here follows a list of telescopes Messier listed and stated he used in 1765-69, published in the Connaissance des Tems for 1807 (here taken from Kenneth Glyn Jones' book; FL means "Focal Length", "Mag." Magnification, unfortunately he normally doesn't give the aperture):

  1. Ordinary refractor of 25 foot FL, Mag. 138x
  2. Achromatic refractor, 10.5 foot FL, owned by M. de Courtanvaux, Mag. 120x
  3. Achromatic refractor, 3.25 foot FL (Dollond), owned by Duc de Chaulnes, Mag. 120x
  4. Ordinary refractor of 23 foot FL, Mag. 102x
  5. Ordinary refractor of 30 foot FL, owned by M. Baudouin, Mag. 117x
  6. Campani refractor, owned by M. Maraldi, Mag. 64x
  7. Gregorian reflector ('Short') 6 feet FL, owned by M. Lemonnier, Mag. 110x
  8. Gregorian reflector 30 feet FL, 6 inch aperture, Mag. 104x
  9. Newtonian reflector 4.5 foot FL, Mag. 60x
  10. Refractor 1 foot FL, 3-inch aperture, owned by M. de Saron, Mag. 44x
  11. Refractor 19 foot FL, of the Paris Observatory, Mag. 76x

As there's always a magnification given, it seems that the idea of exchangeable eyepieces was not yet common in Messier's time.

Although some of Messier's reflecting telescopes had 7.5-to-8.0-inch aperture, they had little light gathering power as their mirrors were made of speculum metal (glass mirrors came in use only in the 1850s).

In his contribution to Sky & Telescope which is reprinted in Mallas' and Kreimer's Messier AlbumOwen Gingerich points out that Messier's favorite instrument was a 32-feet FL, 7.5-inch aperture Gregorian reflector with mag. 104x, not listed above. Bailly has computed that the effective aperture of this instrument was equivalent to a 3.5-inch refractor. Even worse was the situation of the old Newtonian reflector he brought over from Delisle, which was an 8-inch but as effective as a 2.5-inch refractor only, so it was little used, although it seems this was the "original" instrument at Hotel de Cluny, Messier's observatory. Later he preferred to use several 3.5-inch (90 mm) achromatic refractors, which were usually about 3.5 feet long and magnifying 120 times. He selected to use these scopes because they were the best accessible instruments for him.

It remains to state that all of Messier's instruments could probably not compete with a modern 4-inch refractor or 6-inch Newton reflector. Therefore, even moderately equipped amateurs of current days can easily hunt down all the objects he observed and cataloged.

 

Asterisms – Backwards 5

By: Steve Goldberg  (Posted 6/16/2019)

Asterism: a grouping of stars that form a recognizable pattern.
 
Constellation: Hercules
Right Ascension:  16h 36m 00.0s
Declination: +30o 45’ 00”
Magnitude: 7 to 10.6
Size:  24’
.
 
 
 

 

This month’s asterism is named the Backwards 5. It is located in Hercules. This is a faint asterism, but it can be seen.

 

 

 

 

 

 

 

 

It is easily located near Zeta ζ Hercules. The large circle is a typical finder, with the smaller circle the FOV (Field of View) in a 10” telescope with a 32mm eyepiece.

 
 
 
 
 
 
 
 
 

 

 

In the center of this view you can see the “Backwards 5”. However, with certain telescopes, like a Schmidt-Cassegrain with a right angle prism, the 5 appears correct.

 

HAS Online Store

Get Connected!

HAS has begun using RainedOut, a text message service, to communicate late-breaking news about events. Click here to learn more and subscribe!

Night Sky Network