Upcoming Events
Events are open to all members and the general public. Sign up for email event updates by registering with Night Sky Network.
Most of our events happen at the Chabot Space and Science Center. Get directions here.
Next General Meeting
(Note that this meeting will be hybrid, in-person and on zoom/facebook. Our speaker will join us IN PERSON in Classroom 3 & 4 / Kepler-Copernicus), as well as in our on-line meeting.
Meeting will be held at the Chabot Space and Science Center Classroom 4 (the Room formerly known as Copernicus). Please enter through the side gate along the back road of the facility.
Our guest speaker for the evening is Natasha Abrams, UCB
TITLE: Black Holes: Discovering the Invisible
Black holes are among the most extreme objects in the universe. They push the boundaries of our knowledge, holding many unsolved mysteries. This talk will begin with a brief overview of the lifecycle of stars and how stellar-mass black holes form from the explosions of stars at the end of their lifetimes. These are black holes ~3-100 times that mass of our sun. We will then explore how we can detect these objects. Since black holes are invisible, the methods we use to detect them require that the black hole interact with a nearby star or bends space and light. Most methods require that the black hole is in a binary system – when a black hole is in a bound orbit with another black hole or star. Stellar-mass black holes can be found in x-ray binaries, as they accrete matter from the star in a binary orbit with them. They can also be detected in a binary orbit from the apparent wobble of a star orbiting around a massive unseen object. We can also observe gravitational waves which are when the very fabric of space being stretched as two black holes orbit one another until they merge into a single black hole. The only way to measure isolated black holes is using gravitational microlensing . That is when a black hole passes in front of a background star, bending extra light towards us and causing the original star to get brighter and fainter as the black hole passes in front of it. All these methods have different biases and types of black holes that can be found, so it’s with them all together that we can probe the underlying black hole mass distribution.
In the second half of this talk, we will explore supermassive black holes – these are ~100,000 – 10,000,000,000 times that mass of our sun. Supermassive black holes are found at the center of galaxies and can influence the stars and gas nearby them. We’ve detected the black hole at the center of our Milky Way, Sagittarius A*, by tracking the stars nearby in their zooming fast orbits around a seemingly empty space. We can also see the collective movements of stars in the centers of their galaxies to infer the mass of the supermassive black hole found there. In addition, with the invention of techniques used by the Event Horizon Telescope, we can take a “picture” of a black hole, including the glow accretion disk around them. We can also detect booming bright quasars which eject material in powerful jets which can outshine the rest of their galaxy and be detected across the universe. As we explore how we detect black holes from “small” to enormous, we will build the currently known picture of black holes in our universe and probe the very frontiers of astrophysics.About the Speaker
Natasha Abrams is an astrophysics PhD student and Berkeley Fellow at UC Berkeley searching for black holes via microlensing. She is working with Prof. Jessica Lu on photometric microlensing with large surveys, astrometric microlensing, and understanding how binaries impact our statistical understanding of the events we discover. She completed my Bachelor of Arts at Harvard University in 2021 in Astrophysics and Physics. As an undergraduate, she primarily worked with Prof. Christopher Stubbs on microlensing with the Vera C. Rubin Observatory and searching for black hole – variable star binaries via the Light Travel Time Effect.
Telescope Makers’ Workshop
The Telescope Maker’s Workshop is one of few regularly scheduled such workshops in the world! Every Friday from 7 to 10 PM, amateur telescope makers from the bay area meet at the Chabot Space & Science Center and learn how to grind, shape, polish, and figure mirrors for reflecting telescopes, under the guidance of EAS volunteers. The workshop is free; participants pay only for the mirror blanks and grinding tools, which generally cost between $100-$300, depending on the size of the mirror. All the instruction, grinding grit, testing equipment, and camaraderie is free of charge! For more information, email Richard Ozer at pres@eastbayastro.org, or come by the workshop any Friday to see what it’s all about.
Outreach
EAS sends volunteers to schools, libraries, and anywhere curious aspiring astronomers gather. EAS volunteers bring their own equipment or borrow telescopes. Students, parents, and teachers are always thrilled to look through the telescopes and ask questions. You’ll meet all sorts of interesting people and provide a unique and inspiring experience to kids and parents who may have never looked through a telescope before.
Inquire about and request visits by e-mailing EAS Outreach Coordinator Raymond Howard at outreach@eastbayastro.org. Visit our outreach page to find out about upcoming events.
Members Only Viewing Nights (MOVN)
Once a quarter, we schedule a Members Only Viewing Night at the Chabot Telescope Deck for both EAS and Chabot members. This is our opportunity to look through Chabot’s historic instruments and research telescope, as well as bring our own equipment to share in a more quiet venue. The schedule for MOVN will appear in the event calendar below.
Barcroft High Altitude Star Party
Reservations for the Eastbay Astronomical Society’s Barcroft High-Altitude Star Party are now open to members of the EAS, the Tri-Valley Stargazer’s, and the Mount Diablo Astronomical Society clubs. This year’s event will be held the nights of Wednesday August 20th through Monday August 25th. That’s six nights, leaving the site by noon on Tuesday the 26th. Registration is required and now open.
Please read and follow these instructions carefully.
Before sending payments for reservations ($90 per night*, per person), even if you’ve been there before, please contact Don Saito FIRST (barcroft@eastbayastro.org) to ensure the dates you wish to attend are available. You will also be asked to read the current Barcroft Writeup (ver 1.7), as it provides the information you’ll need to have a safe, comfortable stay, and what is expected of guests to this University of California research facility.
So, three steps to apply:
1. Attest in writing/email that you read the current Barcroft Writeup and sign the Waiver.
2. Email Don Saito at the above address to check reservation availability and make reservation.
3. Pay the number of days reserved via PayPal or check/snail-mail.
Barcroft is one the premier amateur astronomy view sites in the world, and it’s slightly less than a day’s drive from the Bay Area to its location in the White Mountains.
Space at Barcroft is limited to a maximum of 25 people per day, so to ensure you get the days you want, make your reservations early. When entering the range of dates you plan to attend, please indicate the starting night (the day you arrive) and the ending night (the date of the evening before you actually leave.)
* This rate is expected to increase in the not too distant future.
Calstar
Spring Calstar 2025 is scheduled for April 23 – April 27 at Lake San Antonio. Fall Calstar will be held on September 17 – September 21. For more information visit https://calstar.observers.org/