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On the left is a Tele Vue 4x Powermate as part of a speckle interferometry system (Figure 6, Genet et al., 2014). Light curve of eclipsing binary on right (Moschner et al., 2021) included data taken with Tele Vue-102.

In this installment, we travel to Kitt Peak in the Arizona-Sonoran Desert to “speckle” binary stars and finally learn what the impressive-sounding Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne group does! (If you missed our prior Tele Vue Scientific installments, you can click to read Part 1 and Part 2).

4x Powermate and Speckle Imaging at Kitt Peak
Wide shot of the speckle interferometry system installed on the 2.1-meter scope at Kitt Peak. A Tele Vue 4x Powermate is the black vertical tube hanging off the bottom of the scope. (Figure 2, Genet et al., 2014).

Introduction Often practiced by amateur astronomers doing planetary work, “lucky”  imaging was invented by professional astronomers to try to “freeze” distortion of starlight passing through our planet’s turbulent atmosphere. This is done by taking many short exposures of a target, instead of one long one. Amateurs usually align and stack the best quality photos to create an image. Professionals use their data to perform speckle interferometry involving complex math. Speckle interferometry is useful in refining the orbits of close binary stars. The introduction to a 2014 paper, “Kitt Peak Speckle Interferometry of Close Visual Binary Stars,” explains how this works.

The resolutions of conventional visual binary observations were seeing limited until Labeyrie (1970) devised speckle interferometry as a way to circumvent seeing limitations and realize the full diffraction-limited resolution of a telescope. The light from a close binary passing through small cells in the atmosphere produces multiple binary star images which, if observed at high enough magnification with short exposures (typically 10 to 30 milliseconds), will “freeze” out the atmospheric turbulence and thus overcome seeing-limitations. Although the multiple double star images are randomly scattered throughout the image (often superimposed), their separation and position angle remains constant, allowing these two parameters to be extracted via Fourier analysis (autocorrelation).

The paper says that this technique, made practical with the introduction of the CCD camera, resulted in an order of magnitude improvement in binary star data measurement over visual observations. Speckle interferometry then became the preferred technique for characterizing close binary stars.

Camera System and Observing Team
Dr. Russell Genet, of California Poly, led the Kitt Peak study we’re discussing here. He says that the study group was composed of an “eclectic mix of undergraduate and graduate students, and advanced amateur and professional astronomers” that rotated in and out over the two, multi-night, observing runs allotted for the study. This resulted in multiple papers from teams within the groups —all using the same optical setup.
Tele Vue 4x Powermate (black vertical tube) in the focuser (yellow) is part of the speckle interferometry system installed on the 2.1-meter scope at Kitt Peak for the study. (Figure 6, Genet et al., 2014).

Their gear was also an eclectic mix of products from the amateurs and professional worlds. It consisted of an Oxford Instruments, Andor Technologies, front-illuminated, Luca-R camera with Orion 5-Position filter wheel connected to a 2″ Tele Vue 4x PowerMate installed into a Moonlite Crayford focuser with a 2″ OPT (TPO) 2x Barlow on the other side of the focuser (to extend the focal plane out to the rest of the optics). This system was installed at the f/7.6 Cassegrain focus of the 2.1-meter Ritchey–Chrétien telescope at the Kitt Peak National Observatory.

Conclusion The first nine-night data run amassed 1.4 terabytes of FITS image data! Among the conclusions was verification that the system was effective for observing close binaries, down to 0.1 arcseconds apart, with the 2.1-m telescope.

The first results on a specific target were published by a team of advanced placement high school students (Adam et al., 2014a). They found that the published orbit of binary system WDS 01078+0425 / BU 1292 was 282.1 years — which was less than the previously published orbit by 3.2 years.

Tele Vue Powermate for Pro or Amateur Astronomers
Tele Vue’s Powermate line is the key to good amplification for visual and imaging. Powermates are available in different barrel sizes and powers to meet your mission needs: 1¼” (2.5x & 5x) and 2″ (2x, & 4x) formats.
Imaging with Powermates is easy: the visual tops all unscrew to accept a specific Tele Vue Powermate T-Ring Adapter for use with standard camera T-rings.
Read more on our Powermate page (mobile site).

Kitt Peak Speckle Interferometry of Close Visual Binary Stars” was published in the Proceedings for the 33rd Annual Conference of the Society for Astronomical Sciences, June 2014.
Product Announcement
M54 Camera Adapter for Tele Vue Imaging System


The M54 thread is becoming popular on full-frame, dedicated astro-imaging cameras and filter wheels/holders. Our new M54 camera adapter has male M54 x 0.75mm threads on one side and our Imaging System female threads on the other. This allows for easy integration of your M54 compatible hardware with our Imaging System accessories and Nagler-Petzval “is” telescopes. 
Variable Star Observations with Tele Vue-102
Light curve of eclipsing binary WISE J205119.0+343149 Cyg. From 4400 images taken between 2010 and 2020. (Moschner et al., 2021)
Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne is a mouthful for English speakers. It translates to German Federal Working Group on Variable Stars (15 fewer letters in English) and bills itself as “an association of around 200 amateur and professional astronomers, mainly from German-speaking countries, who primarily observe and work on variable stars.” Their very professional-looking BAV Journal contains the results of their observations. It is full of papers on eclipsing stellar systems, new variable discoveries, and even transits of exoplanets.

One proficient group of BAV authors is Peter Frank, Wolfgang Moschner, and Klaus Bernhard. Their copious achievements, published in the journal include discovering new variable stars and refining the orbital elements of eclipsing binaries. They do this by imaging stars over long periods of time. Light curves are then generated from their images with C-Munipack software available on

Team member Peter Frank (Velden, Germany) uses a Tele Vue-102 with SIGMA 1603 CCD-camera (Kodak KAF1603ME chip) for this research and is often credited with discovering new variables. Additional observations are done with a 400mm ASA Astrograph located in Nerpio, Spain, and operated by Wolfgang Moschner.

The “Secrets” Behind Tele Vue Telescopes
Tele Vue-NP127is is a dedicated astrograph.
What is an APO Refractor? How does a consumer know their “APO” is an APO? How does Tele Vue use the star Sirius? Why does Tele Vue use the term “exotic glass”? How are our telescopes assembled? Find all the answers on our blog post:  Tele Vue APO Design and Build “Secrets”.
You can find all the papers published by this team by going to the BAV search page and entering in “Peter Frank” to search out his name in the published papers.
Blue Moon August 22nd
A New View of the Moon. On the sidewalks of Los Angeles: a 12″ collapsible Dobsonian reflector with Tele Vue 13mm Ethos and Claude Debussy’s Clair de Lune.

The year 2021 is able to squeeze in four full Moons over the three months of the summer season. They are: 

    • June 24th: Strawberry Moon
    • July 23rd: Buck Moon
    • August 22nd: Sturgeon Moon
    • September 20th: Harvest Moon
In a season with four full Moons the third one is also referred to as the Seasonal Blue Moon. (Not to be confused with the Blue Moon designation for the second full Moon in a month). A Seasonal Blue Moon occurs about every 2.7 years. 

Did you observe, sketch, or image with Tele Vue gear? We’ll like your social media post on that if you tag it #televue and the gear used. Example:
#televue #powermate #kittpeak #speckle

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