New Life for the Bright Star Monitors

Arne HendenPast Director

arne@aavso.orgahenden@gmail.com

HVolunteers, Donors, StaffDick Post, John Centala, Doug Welch, Donn Starkey, Bob Stine, Doug Hodgson, Jim Bedient, Gary Walker, Mike Simonsen, Jaime Garcia, HelmarAdler, Richard Berry, Arne Henden, Ken Menzies, Gordon Myers, Frank Schorr, Dave Cowall, Mike Nicholas, Richard Sabo, George Silvis, Doug George (Diffraction Ltd.), Al Holmes (SBIG), Don Goldman (Astrodon), Bob Denny (DC3 Dreams), Steve Bisque (Software Bisque), Ron Wodaski (TzecMaun Foundation), Alfred Medina, Pierre de Ponthiere (LesveDome), Steve Beckwith (FocusMax) ,Ron Newman (Moonlite), Mike Linnolt, Duane Dedrickson, Peter Nelson, Greg Bolt, Lou Cox, Doc Kinne, Matt Templeton, Damien Lemay, Bill Stein, Tom Krajci, Bob Dudley, Bart Staels, Frank Parks, Sara Beck, Aaron Sliski , Biil Toomey, Jerry Hubbell, Tom Smith, Mike Rice (New Mexico Skies), Chris Stockdale, Muazzez Lohmiller , JoDee Baker-Malony, Willie Buning, Jean-Bruno Desrosiers, Dave Hinzel, Paolo Maria Ruscitti, Richard Sabo, and anyone I missed

A Little History

• Council discussion at 2008 Fall Meeting to create a Bright Star Monitor CCD system to monitor eps Aurand other bright stars. Council members personally funded system

• 2009 – AAVSO receives NSF Citizen Science grant to study eps Aur

• BSM Installed at Astrokolhoz Observatory (Cloudcroft, NM) in April 2009

• Eps Aur starts fading in August 2009• First BSM observations September 2009

Goals

• Show that precision bright star photometry possible with small telescopes

• Show that photometry can be done from bright urban environments, worldwide

• Develop low-cost robotic system• Calibrate comparison stars for bright targets• Obtain first BVRI light curves of bright variables• Testbed for equipment, robotic observing• AAVSO membership benefit

Using BSM

• Need to be an AAVSO member• Simple proposal form, sent to TAC• Observing is automated; you can specify constraints,

or will be taken as priority permits• Images are calibrated (dark subtract/flat field)• Images sent to either/both ftp site and VPHOT• Notification that images are available• Forum for questions/comments/suggestions

Original BSM Specifications

• Measure 2<V<12 (Polaris, eps Aur)• 2.2x1.4 degree FOV (3 square degrees)• 4.5arcsec pixels (not seeing limited)• Expose up to 80 seconds unguided• BVRcIc• Experiment with diffraction gratings,

scintillation

Cost – Original BSM

• Takahashi FS-60CB $1800 (AT65 $600)

• Moonlite focuser $600• SBIG ST8-XME camera $3000 (SBIG donated)

• SBIG CFW-9 filter wheel $600 (SBIG donated)

• 4 filters $600• Celestron CGEM mount $1400 (AVX $600)

• Total $8000 + software (under $6000 possible)

Donated Software

• Mount controlled by TheSkyX (Software Bisque)

• Images Acquired with MaximDL (Diffraction Ltd.)

• Focusing uses FocusMax (Steve Brady)

• Observatory control with ACP, Scheduler (DC3 Dreams)

• Ancillary support with MaxDome, LesveDome, Moonlite all-sky

V1148 Sgr V-band with NGC 6553

NSgr1943

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Original BSM at Astrokolhoz Observatory, Cloudcroft NM (Tom Krajci)

V1148 Sgr V-band with NGC 6553

NSgr1943

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Original BSM

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BSM data marked with blue crosses

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Eps Aur long-term light curve

At RA: 5:01 DEC +44, circumpolar some sites27.1yr period; secondary eclipse 2023?

Global Coverage

Why upgrade BSM?

• Equipment reaching end-of-life (cameras impossible to repair, mounts breaking)

• Lessons learned – mount not robotic (ok if in your back yard)

• Lessons learned – lots of scintillation on short exposures with small telescope aperture

• Lessons learned – 4.5arcsec pixels increase chance of confusion/blending, can’t go faint

• Opportunity to get mounts/OTAs on long term loan from Tzec Maun

Cost – New BSM

• Takashi E-180 astrograph $4800• Paramount ME $18000 (the MyT at $6K works fine)• ZWO ASI183mm-pro camera $1000• ZWO EFW-8 filter wheel $300• ZWO EAF focuser $250• 8 filters $1700• Pegasus Ultimate $600• Miscellaneous adapters, cables $350• Total $27000

New BSM Specifications

• Measure 0<V<18 (Polaris, CV quiescence)

• 1.5x1.0 degree FOV (1.5 square degrees)

• 1.0arcsec pixels (seeing limited, usually binned 2x2)

• Expose up to 300 seconds unguided

• BVRcIc, griz

• Experiment with real-time stacking, daytime observing, diffuser, stacked filter wheels

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New BSM/enclosure at Cape Cod (Gary Walker)

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New BSM

E-180

Paramount ME

ZWO ASI183mm

ZWO EAF

ZWO EFW

Note: 5 of 6 sites identical; BSM_TX uses 101mm refractor and ST8300

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Field of View

1.5x1.0 degrees, Zs, short exposure, daylight

CMOS Advantages

• CCD sensors becoming hard to get (KAF)• Higher QE• Lower read noise (1-3e-)• Low dark current (can run warmer)• Shorter exposures possible (<0.01sec)• Shorter readout time (<0.1sec)• Cheaper ($1000-5000 for cooled versions)• Low power consumption

CMOS Disadvantages

• Few 16-bit ADC sensors; usually 12bit• Pixels typically tiny (2-4 instead of 9-24micron), so

less useful for long focal lengths• Tiny pixels means LOTs of pixels, more storage• Tiny pixels means smaller full well depth• no on-chip binning, so read noise increases• Harder to optimize with gain/offset/mode controls• Amplifier glow

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SU Lyn V-band

One-month continuous coverage 3 sites, 0.02mag SD

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S Ori

7 years of well-covered Mira with hump; period gap

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S Ori

SFRA data highlighted, 5 different BSMs

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S Ori

7 years of well-covered Mira with hump; period gap

For more information

• https://www.aavso.org/bright-star-monitor-section

• Dave Cowall, Section Leader• More volunteers always welcomed!