Welcome to the Starcast for the week of August 17th, 2025. I'm your host, Jay Shaffer, and with me is my co-host, Mike Lewinski.

Good morning, Mike. How are ya?

Good morning, Jay. I'm doing good. Great to be here today.

Good. Let's take a look at space weather from SpaceWeather.com. Mike, what's happening with the sun over the next couple days?

Well, Jay, the lead story this morning is the co-rotating interaction region. That is expected to hit Earth tomorrow. This is basically a case where we have a fast solar wind stream that is overtaking and interacting with a slower solar wind that is ahead of it. And this creates a compressed region that appears to rotate with the sun's rotation, hence the name co-rotating. And when that hits the Earth, we do have a possibility for minor G1 class magnetic storms and high-latitude auroras are possible. So, the official forecast here for us in mid-latitudes is 10% the next day, but jumping up to a 35% chance of an active condition in the 24 to 48-hour window. And that could be a minor storm at a 20% chance. It's unlikely we're going to get a severe storm out of it. However, if you're at high latitudes, your chances of a severe storm tomorrow are approximately 50%, so there's a chance you're going to see a Northern Lights.

Yeah, so that's just sort of like, we're kind of, like, in a lighthouse beam, as the solar wind kind of sweeps across us with the co-rotation with the sun.

Yeah, that's a good metaphor. I like that. So, and what's up in space news this week, Jay?

Well, first, I'll tell you what's happening in the night sky this week.

Yeah, okay. What's happening in the night sky?

So this week in the night sky, on Monday, August 18th, Titan cast his shadow on Saturn. Every 15 years, Saturn's largest moon repeatedly crosses Saturn's face from the Earth's viewpoint, and more visibly, it cast its very tiny black shadow onto Saturn's face. A series of these events is now underway. They will continue every 16 days until October. Monday, Titan Shadow crosses Saturn from 5:52 to 10:00 am Universal Time, August 19th. Or in Eastern Daylight Time, that's from 1:52 a.m. to about 6 a.m. Wherever you are, Saturn rises in the evening and is in its highest in the hours before dawn. So all of North America again gets a chance to see that this shadow transit. However, you'll need a fairly large telescope to view or capture this event. And then on Saturday, August 23rd, is the new moon. To be exact, it will be at 2:07 a.m. Eastern Daylight Time on the 23rd. Now, let's take a look at some space news. Mike?

Thanks, Jay. The Hubble Space Telescope has imaged an interstellar comet. This icy body was discovered by the NASA Asteroid Terrestrial Impact Last Alert System, or ATLAS, on July 1st of this year. It was 420 million miles from the Sun at that time. Atlas is an asteroid impact early warning system that was developed by the University of Hawaii. After its discovery, the comet was assigned the designation 3I slash Atlas, and that would be the third interstellar object that has been assigned that designation. The data collected by Hubble has enabled astronomers to estimate the size of the comet's solid, icy nucleus. This is pegged upper limit has a diameter of 3.5 miles, or 5.6 kilometers. A lower limit on the nucleus size is just 1,000 feet, or 320 meters across. According to the researchers, these limits are sound, although Hubble cannot see the solid nucleus. Jay, what have you got?

Astronomers have discovered a new kind of supernova. Dubbed SN for supernova, obviously, 2023 for the year it was discovered, Zkd, which they believe it was caused by a massive star trying to consume a black hole companion. The explosion was initially detected by a new artificial intelligence algorithm in July 202, which allowed for an immediate follow-up observations from various telescopes. The study, led by a team from the Center for Astrophysics, found that a star of about 10 solar masses was in a deadly orbit with a black hole of similar mass. The star began to envelop the black hole, which in turn pulled material from the star until it catastrophically exploded, leaving behind a single, heavier black hole. The supernova was triggered by a "catastrophic encounter with a black hole companion," according to the lead author, Alexander Gagliano. The analysis suggests that the massive star and a black hole were in close orbit, and the black hole's gravitational stress on the star ultimately caused the explosion. So in the end, the black hole wins. So today, Mike and I are going to talk about Twilight Don and the Holy Grail of astrophotography. And so, when we talk about the Holy Grail, we're talking about time-lapse photography, and so we're going to talk about some techniques today in which we can capture the entire night sky, because this has always been a challenge for time-lapse photographers, in that the sky goes from when the time the sun goes down, it gradually gets darker and darker and darker, and then you have to constantly adjust the exposure of your camera to get optimum exposure when you're shooting a time lapse. So that's what we call the Holy Grail. So, Mike, tell us a little bit about how you try to get the best exposures for your night time lapses.

Sure, Jay. I'll also add, right at the outset, that this is the same challenge we have when time-lapsing and eclipse, whether it is a solar eclipse or a lunar eclipse. You're going from a very bright full moon, or complete disk of the sun to a completely eclipsed, very dark disk. And a continuous change of exposure is necessary for a smooth, that's the Holy Grail, is the smooth transition from bright to dark, or from dark to bright. So, I have two cameras that I use when I do time lapses. I have a Sony Alpha 6300, and then A7R3. And the sort of poor man's holy grail method is to put the camera into aperture priority mode. And then allow the, set up a time lapse with all the usual preparations of fully charged batteries, perhaps an external battery pack, stabilized on a tripod, and then to allow aperture priority mode for the camera to continuously adjust shutter speed based on a light meter reading. And my experience has been that the less expensive A6300 can do a really good job of this. Most nights, I'm able to get a pretty smooth transition from sun up in the sky, visible in the frame, to stars. Now, sometimes there is some flickering, and that's kind of the unwanted outcome of doing an attempted holy grail with aperture priority. The A7R3 is much less capable of this method. The aperture priority, no matter what settings I try, I don't get the or if I do get, I do get a gradual transition into night. The end point is too dark, and yes, there are stars visible, but it's not a very, not very many stars. Most of the sky is just black. So, to do a more professional and smooth transition from bright sun to complete darkness requires some specialized tools. And I've tried a number of these over the years. In fact, I've got sitting on my desk the latest Myops, that's M-I-O-P-S Smart Plus. And it's my third MyOps. They've gone through some iterations. And it's a multi-purpose smart trigger that can do a lot of things, including detecting lightning, triggering based on sound. So you can do high-speed photography of, say, a balloon popping. I bought the latest one because it promises a storm lapse mode, where you set up a lightning storm, and you're taking a photo every 5 seconds. But if it detects there's a lightning that's about to strike, that's in between those frames, it'll also capture that. And it promises a holy grail mode, which utilizes the bulb feature of the camera. So, with bulb, you have and this harkens back to the days when your shutter was actuated with burst of air. So you'd have an actual bulb that you would squeeze, and as long as you held that bulb, then the shutter would remain open. And so the idea with a modern DSLR is that you put your camera into bulb mode, and then the trigger, whether it's a MyOps or I also have a LR time-lapse Pro Timer 3 that works in the same way. The timer, the you say, I want to start with, say, 1/500th of a second exposure, because it's bright sunlight. And my end exposure is going to be 10 seconds in complete darkness. And so, in bulb mode, the external timer can exactly specify the intervals that you want. So, starting with 1/500th of a second, the trigger activates the bulb mode, and then after 500th of a second, it deactivates it. So you get an exposure that's exactly that length. And then you program a sequence so that, estimating that from bright sunlight to astronomical twilight is happening over the next 2 hours, you would gradually increase the length of the exposure. And the camera operating in bulb mode is just going to simply start and stop when the external timer tells it to. And the piece of software, LR time lapse that is associated with the Timer Pro 3 is really the industry standard for Holy Grail. It was developed explicitly to do this task. So you can take a sequence of exposures, and there still may be some flickering, and what it does is it will blend them together in a way that eliminates the flicker, so that you get a very smooth transition from bright light to complete darkness. And I've used it a little bit. It's a lot of work to get all this done right, and most of the time, it's more time and effort than I have to do on a daily basis. So, I do use the aperture priority mode on the regular. In fact, I was up at 4 a.m. today to walk out to my time-lapse setups and to switch from manual mode, long 10-second exposure into aperture priority mode. And if you're going to try that poor man's version, just using aperture priority mode, you have some choices to make with regard to ISO? Are you going to set ISO automatic, so that it can adjust both the exposure duration and the ISO at the same time? You also have choices related to light, white balance. And this is why, if you're really serious about Holy Grail, there's no substitute for shooting raw and using a tool like LR Timelapse. The reason here is that, let's assume you're going to have a sunny day on a sunny night at sunset. So you want to an ISO, or sorry, a white balance that is tuned to bright sunlight. Well, as you get into full darkness, I often find that bright sunlight, white balance is not very pleasing. It's it can be a green, brown, yellow-brown, it's it's kind of sickly looking to my eye. And so, I much prefer. Normally, if I'm shooting under a dark sky, I will be shooting with a cool white light balance. It's the most pleasing of all the preset options in the camera. And I get the nicest color in the Milky Way and the night sky. So, having your sequence shot in RAW then allows for an intelligent blending of white balance transition from bright sun to cool white, or whatever else you end up with as your target. There really isn't a correct or proper white balance setting for dark sky. Our eyes don't see color at night in the night sky. Usually. So, it's really more of an artistic choice to be made. So, those are kind of some of the considerations. There's additional options such as if I'm going to use aperture priority mode. Instead of bulb with an external, am I going to set interval priority? I usually turn that off, but some people would say that it should be on. There's also the question of the metering mode. Is it full screen, average, or center, or spot? And these will have different outcomes, and the only way to really know is to try them out. I do see people recommend, just go with center spot, don't overthink it. I see people suggesting that interval priorities should be on. The consequence there, if you turn interval priority off, is that your interval between frames is going to change. Aperture priority is going to say, let's say I have a 5-second interval. And I'm starting out at 1/500th of a second exposure. So I'm getting an exposure every 5 seconds. But once my exposure time, as calculated by aperture priority, goes to 6 seconds, I'm no longer able to get a frame every 5 seconds, so that the time lapse is going to appear to speed up as it gets darker. And that's something that, I think a lot of people who are shooting for the Holy Grail of a very smooth, flicker-free transition would also say that having a constant frame rate, or a constant time rate, is as equally important in that Holy Grail. So, I'm kind of a maybe respected Grail, but not quite Holy Grail level. Most days, and that's just due to the real length of time for post-processing and constraints that I have with other responsibilities. So, I think that's the those are the basics, Jay.

Okay. Okay, well, that was pretty deep for the basics. Yeah, and I've had much the same experience, and I generally do use the method of setting the aperture priority, and my particular cameras, when I'm doing the wide-angle time lapses is they have kind of a limit of exposure, they only go up to about 15 seconds of exposure when you're in aperture priority. So, they get to a certain point, and then, basically, they would be under-exposed. And so and then, like you were saying that you go out and you switch it from aperture priority to manual mode. And so that's basically trying to time that out perfectly to get to the point where it's just gets to that 15 seconds of exposure, and then, and then basically then it picks it up from there. And often I find when I go into a manual exposure, which I usually set at 25 seconds in my case, with my particular camera. And so my typical nighttime time-lapse exposure is 25 seconds with a 30-second interval at f2.5, and ISO 6400. And so, when I switch over to to manual mode, of course, and there's a difference between that 15 seconds of exposure and 25 seconds of exposure, so there's always kind of a gap or a place where I will be overexposed for a short period of time. And so, one of the things I want to talk about is the kind of the duration of the kind of the Holy Grail timing. And so, there's when we talk about twilight. So, when we talk about sundown, and so when the sun goes below the horizon. The center of the sun goes below the horizon. Up until about the sun the center of the sun is 6 degrees below the horizon. That's what we call civil twilight. And so, Sybil Twilight is that just after the sun goes down, and you could probably still throw a frisbee in the park, and the park lights might be coming on, and you might see a bright star, a bright planet, like Jupiter or Venus, and maybe a magnitude one or two star, and so and then. What follows civil twilight is what we call nautical twilight. And that's between when the center of the sun is between 6 degrees below the horizon and 12 degrees below the horizon. That's what we call nautical twilight. And it got named as nautical Twilight is because that's when the first bright stars start to appear, and back when they were doing nautical navigation via sextant and we're viewing the stars was basically how they would position themselves around the globe. So that and also, it's when the sky is dark enough that you can't really see the horizon of the sea, so that's why it got kind of named Nautical Twilight. And so in that period, it's still pretty much overexposed for for what we would do for a nighttime lapse. And then, finally, we would reach what we call astronomical twilight. And so that's when the sun is at least 12 degrees below the horizon to about 18 degrees below the horizon. And so, there's still some twilight and residuals. Skylight from the sun going down, and but this is the kind of the period where we start to be able to pick up some of the dimmer stars, dimmer planets, and start to be able to see the Milky Way before we reach, the final stage, which is kind of full nighttime, which is when the sun is over 18 degrees below the horizon. And so, some of the things that, a lot of times what I'll do is I'll just basically say, I mean, time lapse is just gonna go from astronomical twilight through what we call astronomical dawn. And so, with dawn, we have the exact reverse of these twilight stages, so we have an astronomical dawn, a nautical dawn, a civil dawn, and then we have sunrise. And so, you could just do your time lapses from 18 degrees below the the when the sun is 18 degrees below the horizon until it's about 18 degrees below the horizon before dawn. And so there's actually charts and software out there that will tell you what that exact moment is? And so that is one method where you can actually start your time lapses in them during whatever astronomical twilight is. And one more thing I'm going to add about talking about Twilight is that the period of these twilights changes over the seasons. And the reason for this is that the sun moves at an angle once it crosses the horizon. And so, during the equinox periods, this the son would be traveling almost vertically below the horizon, or vertically, coming up above the horizon. And so that 6 degrees below the horizon would be a shorter period of time than it would say during a solstice, where the sun is traveling at an angle as it goes below the horizon. And so, to get that vertical 6 degrees below the horizon to go into nautical twilight, it would take a longer period of time. And so this is why, in the summertime, sometimes between the time that sun goes down to when we get to astronomical twilight can be 90 minutes. And so, and so that is one of those things where the sun might not go down till after 8 PM, daylight time, and then you have to wait another hour and a half to basically start your time lapse. So, that's just kind of a digression into talking about Twilight, and kind of understanding Twilight, and Twilight is the period that we want to approach this, kind of Holy Grail with. And so, and I'm gonna throw it back to Mike for some more thoughts on how to approach this and the Holy Grail. Right?

Yeah, that brings up the idea of using an app like the Photo Ephemeris, which is available for iOS, but not Android. However, there is a Photo ephemeris website which has a free account, you can log in. And it basically lets you visualize sunrises and sunsets for your location. It's also useful for other special events, including eclipses. And so it's very, very handy application that, if you're using iPhone, you probably want to and you want to get serious about this, you want to download the photo ephemeris app. Ephemeris being a word that means a book of tables that have a trajectory of astronomical objects in the sky over time. Some Yeah, go ahead.

Okay, yeah, I was going to recommend another app that's very similar to that, that is both Android and iOS, and it's called Photo Pills. And photo pills has not only, it's basically has a lot of different photographic things, including augmented reality for basically charting where the moon or the sun is going to rise. So if you're getting these full moon rise shots, that's one of my favorite little apps that we'll actually use augmented reality with your phone to be able to pinpoint exactly where the moon's gonna come up across the horizon.

Yeah, it can be really impressive to exactly have your subject framed in advance, so that when it does first start to appear, you're already shooting. I was able to do that with the conjunction of Jupiter and Venus last week, but only because I had been up for a couple nights, and I paid close attention to exactly where it was appearing. I did not use an app for that. Another tip that I wanted to mention relates to what you were talking about, your aperture priority maxing out around 15 seconds. Sometimes what I like to do is I in auto ISO, you can set a minimum and maximum value. And so, you can often, depending on your camera, use this to influence the progression of the interval of exposure. So, for example, in my A7, I might be shooting full dark, it 10 seconds for 12,800 ISO, sorry, $128,000 ISO. And what I can do, though, is I can set in the auto ISO a lower value. Say, 3,200. And what that's gonna do is the camera, my at least my camera, will bump up ISO, trying to keep the exposure times short. But once it hits that maximum auto, ISO value of $3,200, the only way it can compensate for darkening conditions is by lengthening the exposure time. And so, even in aperture priority, you have an extra tool there. Again, it, it's going to require experimentation. Experimentation with the specific manufacturer of camera. Because there's no guarantee that they're all going to work exactly the same. But, I do like, and have played around with, my auto ISO maximum values in order to force the camera aperture priority to start taking longer exposures at an earlier time. And I'll just add that the reason why I like to do that is as I'm doing Holy Grail, the thing that I'm really hoping to get is a very, very nice meteor shot in twilight. Where the landscape is much more visible. And we get a really nice, bright meteor. Well, if the camera is taking, a one-third of a second exposures. Because it's ramped its ISO up to, 128,000. I'm not going to get that meteor. It's it's not the odds of, in a 5-second interval, that one-third of a second exposure happening exactly as that perfect meteor occurs. It's very low. I mean, it's just it's just math there, and whereas, if I've set a low IS. Iso at, say, 3200, now the same, instead of being a one-third, I'm looking at having a full, 5 seconds, exposure time in that 5-second interval. And so I'm going to capture if there's a meteor in that window, I'm going to capture it.

Yeah, that's and that's also one of the things that often happens during twilight is the ability to view comets, because most comets, when they get to their brightest, they're close to the sun, so therefore close to the horizon, at dawn or at dusk. And so, another thing about kind of shooting in this, the Holy Grail range, or the twilight range, is the ability to capture comets. Well, I'm gonna wrap this up there, Mike. I think we've done a pretty good deep dive into how to do the Holy Grail type of exposure for capturing time lapses with time-lapse photography. And, I just wanted to add that my holy grail is to be able to afford one of those nice Sony A7r3 cameras. So, anyway, I want to thank all of our listeners for checking out this podcast, and be sure to comment, like, and subscribe, and let us know what you'd like to hear more about. You can also check out our individual websites and see Mike's wonderful Holy Grail time lapsers at WildernessVagabonds.com. And my, my, sordid attempts at Skylapser.com. And if you'd like to help us out, you can buy us a coffee at buymeacoffee.com slash skylapser. The intro music is fanfare for space by Kevin McLeod from the YouTube Audio library, and from the Deep Sage 9 Observatory, this is Jay Shaffer and Mike Lewinski. Wishing you all clear skies.