TELE VUE SCIENTIFIC PART 3
+ New Product Announcement!

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.

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Tele Vue-76 Gallery: Catching Up with Diego Cartes!

Back in December 2018, we featured some spectacular wide-field, deep-sky images by Diego Cartes Saavedra in Chile. All the images were taken with his Tele Vue-76 APO refractor and Tele Vue TRF-2008 0.8x Reducer/Flattener. This combination achieves a 380mm focal length at f/5, ideal for imaging large swaths of deep sky. You can still read the original blog at Tele Vue-76: Imaging the Southern Hemisphere. At the end of that post, we wished Diego continued success in his astrophotographic journey.  Ever since, we’ve followed his progress through his postings on the AstroBin imaging hosting platform for astrophotographers. We felt it was time to “catch up” with him and post some of his latest captures in this gallery blog.

NGC 6188 ─ The Fighting Dragons of Ara (Hubble Palette)
The Fighting Dragons of Ara (Hubble Palette) by AstroBin user Diego Cartes. All rights reserved. Used by permission. Imaging was done with Tele Vue-76 APO refractor, Tele Vue TRF-2008 0.8x Reducer/Flattener (converts Tele Vue-76 to 380mm f/5), ZWO ASI 1600MM Cooled Pro monochrome camera, ZWO 7x36mm Filter Wheel (EFW), and guiding with ZWO ASI 290mm Mini ─ all riding on a Celestron Advanced VX mount. Imaged with bin 1×1 through ZWO OIII -7nm 36mm: 59×900″ (14h 45′), ZWO SII -7nm 36mm: 78×900″ (19h 30′), & ZWO H-alpha 36mm: 69×600″ (11h 30′) for an amazing total integration time of 45h 45′.

Prior generations of supernovae explosions spread dust and gas in this complicated region of space. Continued explosions compressed this material and sparked the formation of new massive stars. Stellar winds from these stars intricately sculpted the region into areas of glowing gas, reflection nebulae, and dark clouds of dense matter. The resulting dark, dusty lanes conjure up images of two dragons. Light from open cluster NGC 6193 illuminates the large blue reflection nebula where the dragons face off. The dense, blue object at the lower-right is pk336-00.1 (also NGC 6164 & NGC 6165) ─ an emission nebula formed from the expanding outer layers of a giant, hot, O-type star at the center. Around this compact object is the faded outer ring of reflected blue dust from earlier shedding events. This image was awarded an AstroBin “Top Pick” nomination.

Sharpless 2-308 (Bicolor palette)
Sharpless 2-308 (Bicolor palette) by AstroBin user Diego Cartes. All rights reserved. Used by permission. Imaging was done with Tele Vue-76 APO refractor, Tele Vue TRF-2008 0.8x Reducer/Flattener (converts Tele Vue-76 to 380mm f/5), ZWO ASI 1600MM Cooled Pro monochrome camera, ZWO 7x36mm Filter Wheel (EFW), and iOptron iGuider ─ all riding on an iOptron CEM70G EQ mount. Imaged with bin 1×1 through ZWO OIII -7nm filters 51×900″ (12h 45′) and ZWO H-alpha 66×900″ (16h 30′) for a total integration time of 29h 15′.

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