Buying Guide
The Telescope Simulator on Mobile — Complete Field Guide
This is the mobile-first guide to the AstroEquip Telescope Simulator — the same tool as the desktop version, but reorganised around the four-tab bottom drawer, touch gestures, and the way you actually use the simulator at the imaging site. Every section maps to a panel you can swipe up. On a desktop or laptop? See the desktop guide — the toolbar layout is very different.
In this guide
- The mobile layout — sky, tab bar, and drawer
- Gestures — pan, zoom, rotate
- Object tab — find a target
- Gear tab — autofill your gear
- Gear tab — manual entry
- View tab — filter, rotation, exposure
- Stats tab — sampling, trailing, light budget
- Calc segment — sub-exposure calculator
- The HUDs over the sky
- Save, share, and saved setups
- At the imaging site — three field workflows
- Test a gear upgrade from your phone
- Tips, gestures, and gotchas
1. The Mobile Layout — Sky, Tab Bar, and Drawer
The mobile UI has three persistent regions:
- Sky viewport — the dark area in the middle. Always full-bleed when the drawer is closed.
- Mobile header (top) — small Save, Info, Tutorial, and Share buttons.
- Tab bar (bottom, four icons) — tap any tab to slide up its panel.
The four tabs are:
| Tab | Opens panel for… |
|---|---|
| Object | Searching, popular target chips, navigating to coordinates |
| Gear | Telescope / camera / mount — autofill or manual entry |
| View | Filter mode, projection, rotation, exposure brightness |
| Calc | Stats readouts + sub-exposure calculator (segmented switcher inside) |
Tap a tab to slide up its panel. Tap the same tab again to slide it back down. The sky stays live behind the drawer — you can drag a target into the part of the sky still visible above the open drawer if you need to frame while a panel is open.
Drag the drawer to resize
The small handle at the top of the drawer is draggable. Drag down to make the drawer smaller (more sky visible), drag up to make it larger (more panel visible). The drawer remembers its last height across opens.
2. Gestures — Pan, Zoom, Rotate
| Gesture | Action |
|---|---|
| One-finger drag | Pan the sky. Framing rectangle stays centred. |
| Two-finger pinch | Zoom the sky in/out. Smooth across the full DSS2 resolution range. |
| Two-finger rotate | Rotate the sky (POV mode) or the framing rectangle (FOV mode). Mode is set in the View tab. |
| Tap an object | Pulls up a name label. |
| Tap the ⓘ button in the HUD | Opens a quick info search for the current target. |
3. Object Tab — Find a Target
Tap the Object tab (left-most in the bottom bar). The panel slides up with:
- Search box at the top — type any object name (M31, NGC 7000, IC 1396, etc.).
- M / NGC / IC / B catalogue pills just below the search — tap to filter the autocomplete to a specific catalogue.
- Popular targets grid below — tap a card to jump straight to that object (M42, M31, Veil Nebula, etc.).
- Go to coordinates at the bottom — RA/Dec entry pair, for centring on a specific point.
Once you've picked a target the drawer can stay open or you can close it (tap the active tab again). Either way the framing rectangle and the HUD update live.
4. Gear Tab — Autofill Your Gear
Tap the Gear tab. The panel that slides up has three gear cards: telescope, camera, and mount. Each starts with a text input.
Type your model
Type the actual product name into the input — e.g. "Esprit 100", "ASI2600", "AM5", "RedCat 51". As you type, the dropdown shows matching products from the AstroEquip catalogue. Tap a result.
The simulator fills in:
- Telescope: focal length, aperture, focal ratio, optical design, weight.
- Camera: sensor format, pixel size, sensor dimensions, camera type (OSC / mono / DSLR).
- Mount: mount type (EQ GoTo / Star Tracker / Alt-Az), payload, weight.
The framing rectangle, HUD, Stats, and Calc readouts all update instantly. Switch by tapping SWAP on the populated card. Remove with the × button to return to the autofill input.
5. Gear Tab — Manual Entry
Scroll down inside the Gear panel. Below the gear cards you'll find a row of inputs you can use without going through the catalogue:
| Input | What it sets |
|---|---|
| FL | Focal length in mm. Printed on every scope and most lens barrels. |
| Sensor | Sensor format. Each option encodes width × height in mm. |
| Pixel | Pixel pitch in µm. Drives the image-sampling number in Stats. |
| Mount | EQ GoTo / Star Tracker / Alt-Az. |
Autofill and manual entry can be mixed — autofill a telescope, then override the focal length to simulate a reducer or extender. Nothing else breaks.
6. View Tab — Filter, Rotation, Exposure
Tap the View tab. The panel has:
- Filter mode — visual / L-eNhance / Hα / OIII / SHO / HOO / broadband LP. Same options as desktop. When you pick a narrowband mode, a small band-intensity bar pops up at the top of the screen so you can tune the channel weightings.
- Projection — leave on Default unless you're shooting through a fisheye or hyperbolic corrector (RASA / Hyperstar).
- Rotation — number input plus three mode buttons: FOV (rotate the framing rectangle only), POV (rotate the sky only), FOV+POV (rotate both together as one unit). Tap reset (↺) to return to 0° = celestial north up.
- Exp — exposure slider for image brightness. Cosmetic only — doesn't affect any calculations.
7. Stats Tab — Sampling, Trailing, Light Budget
Tap the Calc tab (the right-most icon). The panel that slides up has a segmented switcher at the top with two options: Stats and Calc. Tap Stats for the readouts panel.
Image sampling (arcsec/pixel)
| Sampling | Verdict |
|---|---|
| < 1.0"/px | Over-sampled — consider a reducer. |
| 1.0–1.5"/px | Excellent — high-res deep sky in good seeing. |
| 1.5–2.5"/px | Good — matches typical seeing. |
| 2.5–4"/px | Coarse — fine for nebulae and wide-field. |
| > 4"/px | Very coarse — wide-field only. |
Star trailing limit
Maximum sub-exposure length before stars streak at your focal length and mount combination. EQ GoTo with guiding is effectively unlimited. A star tracker at 600mm is around 60s. Alt-Az at 1000mm is unusable for deep sky.
Light budget
Total integration time needed for a clean image given your target, Bortle value, and filter choice. Galaxies under Bortle 6 with no filter: 3–5h. Same galaxy at Bortle 3: 1–2h. Narrowband targets: 3–5h per channel even under good skies.
8. Calc Segment — Sub-Exposure Calculator
Tap the Calc tab, then tap Calc in the segmented switcher at the top of the panel. This is the sub-exposure calculator — it answers the most common planning question: how long should each sub be, and how many do I need?
The four camera preset buttons
Four taps to set sensible read-noise + dark-current values for your camera class:
Modern cooled CMOS
ASI2600MC, ASI2600MM, ASI533MC, ASI533MM, ASI6200, QHY268. Read noise ≈ 2e⁻, dark current ≈ 0.001e⁻/s at -10°C.
Older CCD cameras
QSI, SBIG, Atik, older Moravian CCD bodies. Read noise ≈ 3.5e⁻, dark current ≈ 0.002e⁻/s.
Uncooled CMOS, mirrorless
Modern mirrorless (Sony α7, Canon EOS R), ASIair bodies in OSC mode without cooling. Read noise ≈ 5e⁻, dark current ≈ 0.01e⁻/s.
Older DSLRs (Canon, Nikon)
Stock DSLRs and modified DSLRs (Hα-mod Canon EOS Ra, modded Canon 600D, etc.). Read noise ≈ 8e⁻, dark current ≈ 0.05e⁻/s.
Tap a preset and the read-noise + dark-current fields autofill. You can edit either by hand if you know your camera's specific values from the manufacturer spec sheet.
Sub length + number of subs
Type your planned individual exposure time (in seconds) and how many you intend to capture. Typical values for deep sky: 30–300s subs, 30–200 total.
What's pulled from your simulator setup
- Bortle scale — from your gear panel.
- Pixel scale — focal length × pixel size.
- Sky background brightness — derived from Bortle + pixel scale.
- Narrowband toggle — divides sky-background contribution by ~20× when on.
The four result cards
| Result | What it tells you |
|---|---|
| Optimal sub | The sub length at which sky noise dominates read noise by ~10×. Below this you're read-noise-limited; above gives diminishing returns. |
| Total time | Sub length × number of subs. Real sessions lose 15–25% to dithers, flips, focus checks — round up. |
| Stack read noise | Effective read noise after stacking (R / √n). Halving it requires 4× more subs. |
| SNR gain | Signal-to-noise improvement vs. a single sub. From 25 to 100 subs only doubles SNR. |
Noise breakdown bar
The horizontal bar below the results shows, per sub, what fraction of total noise comes from each source. Use it to diagnose:
- Read-noise-dominated: subs too short — lengthen them.
- Sky-dominated: the regime you want. More subs help; longer subs help less.
- Dark-current significant: sensor too warm or subs longer than needed.
9. The HUDs Over the Sky
Two information overlays float over the sky viewport:
Target HUD (top-left)
Shows the current target name + field of view (W × H in degrees).
- ◎ Field toggle — switches between Field mode (auto-names whatever notable object is centred) and Locked mode (stays on what you last searched for). Useful during exploration.
- ⓘ — opens a quick info search for the current target.
Nearby HUD (bottom-left)
Names notable deep-sky objects near your framing rectangle. Pops in only when there's something worth naming — useful for spotting "I'm one rotation away from also having M82 in this frame".
10. Save, Share, and Saved Setups
Save a screenshot
Tap 📷 Save in the mobile header (top-right). The simulator generates a PNG of the current framing — sky, framing rectangle, and any filter rendering all baked in. Save to your camera roll.
Share a link
Tap Share ↗. Copies a URL that re-creates the exact view: target, gear, Bortle, rotation, filter mode. Paste into a forum question, text it to your imaging partner, or save it to your notes.
Save the full setup to your account
Open the Gear tab and scroll to the bottom — there's a 💾 Save current setup button. Stores the full gear configuration to your AstroEquip account (signed in) or to local storage (signed out). Once signed in, saved setups sync across devices.
11. At the Imaging Site — Three Field Workflows
Three concrete walkthroughs for using the simulator on your phone, in the dark, between setup steps.
Field workflow 1 — "I just finished polar alignment. What do I shoot?"
Open the simulator on your phone.
Sign in if you haven't — your saved setups will be there.
Load your gear (autofill or saved setup).
If you've saved a setup before, swipe up the Gear tab, scroll to Saved setups, and tap the right one.
Set Bortle from your actual location.
Even if you're at a darker site than usual, this matters — your light budget depends on it.
Enable Field mode on the HUD.
Close the drawer. One-finger pan around the part of the sky you can actually point at (most mounts can't image close to the horizon). The HUD will name candidate targets as you pass over them.
Open the Calc tab.
Tap the segmented switcher to Stats first. Check light budget vs. your remaining session time. Then flip to Calc — your camera preset will likely already be set from a prior session, so just check the optimal sub. If your real sub time matches it, you're sky-noise-limited; you're good.
Field workflow 2 — "Cloud just rolled in over my target. Reframe to another?"
Look up at the actual sky.
Identify which patch is still clear.
Open the Object tab.
If the clear patch is near a known constellation, search for a bright reference (M31, M42, Vega, Capella).
Pan with Field mode on.
Find a target inside the clear patch. The HUD names it for you.
Check star trailing.
Stats tab. If your mount can handle the target's altitude (lower targets have more atmospheric refraction drift), you're good.
Slew there and start integrating.
You've lost maybe 10 minutes to the cloud — much better than abandoning the session.
Field workflow 3 — "How long should I keep going?"
Open the Calc tab → Calc segment.
Set sub length to your actual current sub length, number of subs to how many you've already captured.
Total time → how much you've actually integrated so far.
Compare against Stats → light budget.
If light budget is 4h and you've integrated 2h, you're at 50% — there's clear benefit to keeping going. If you're at 80%+, the next hour is diminishing returns and you can pack up early if it's late.
Cross-check the noise breakdown.
If sky noise dominates the per-sub noise bar, you're collecting the right kind of data — more subs help. If read noise dominates, you should have been doing longer subs all along — note that for next time.
12. Test a Gear Upgrade From Your Phone
Same simulator, same calculator. Phone-friendly upgrade decisions:
Upgrade test 1 — "Is a faster scope worth it?"
Open the Gear panel.
Note your current scope's focal length, focal ratio, and the Stats tab's sampling number.
Tap SWAP on the telescope card.
Type the model you're considering — say "RASA 8" or "RedCat 71". Pick it from the dropdown.
Compare the framing on the same target.
If it's still in the drawer, close it and look at the sky. Pan to your usual target. The framing rectangle is now the new scope's; compare to what you saw before mentally.
Open Calc tab.
Run the calculator with the same camera preset. The new scope's faster f/ratio shortens the optimal sub. If your mount can't track that short → free win.
Upgrade test 2 — "ASI533 vs ASI2600 for my targets?"
Autofill ASI533MC. Frame your favourite target.
SWAP to ASI2600MC.
The framing rectangle changes — 1" sensor → APS-C is a big jump. Look at how many objects fit.
Open Calc tab for each.
Set the cooled ASI preset. Run with your typical sub length. The lower read noise of the ASI2600 lets you shorten subs without becoming read-noise-limited.
Decide based on framing.
If the targets you care about overflow the ASI533, the ASI2600 is the upgrade. If they fit, the ASI533's smaller image circle is more forgiving on cheap optics.
Upgrade test 3 — "Tracker → EQ mount, is the jump real?"
SWAP the mount card from Star Tracker to EQ GoTo.
Open Stats. Star trailing limit jumps from 30–60s to effectively unlimited.
Open Calc tab.
Your existing sub length may be far below the optimal sub. With an EQ mount + guiding, you can finally hit optimal — much shorter total session time for the same SNR.
13. Tips, Gestures, & Gotchas
Use Field mode while panning the sky.
The HUD names what you're looking at. Best way to discover targets near where you planned to image.
Two-finger rotate works.
Twist on the sky to rotate. The mode (FOV / POV / FOV+POV) you've selected in the View tab decides what actually rotates.
Calculator before you start integrating.
Running it in the dark for 30 seconds at the imaging site catches "subs too short" mistakes that you'd otherwise only learn during processing the next day.
Save your setup at home, not in the field.
Once a setup is saved, signing in on your phone at the imaging site loads it instantly. Don't fumble with autofill in the cold.
Phone landscape mode helps a lot.
The drawer panels are designed for portrait, but landscape mode gives more sky-map real estate. Worth trying for the framing checks.
Pinch-zoom doesn't zoom the page chrome.
Locked intentionally so pinch can be used for sky zoom. If you want bigger UI text, use your browser's text-zoom menu.
Tutorial replay is in the mobile header.
The Tutorial button up top runs the same 10-step mobile tour you saw on first load. Useful refresher if you haven't opened the simulator in a while.
Open the simulator and plan tonight's session
The simulator is meant to be used on the device you have nearest at the imaging site — usually a phone. Sign in, load your saved setup, and decide what to shoot based on real numbers rather than guesses.
Open the Telescope Simulator →