Worldwide Telescope Usage - a Survey of Astronomers
Help NASA gather data about astronomy activity. We want to determine--at a given time of night, at a given latitude--how many people are using a given size of telescope, how many are visual observers vs. astrophotographers, etc. Your responses to this survey will help us answer these kinds of questions, so thank you! If you don't know the answer to a question, just leave it blank. (We promise not to take off any points.) If you use multiple types of telescopes and feel that the questions are not flexible enough to adequately reflect your usage habits, feel free to take the survey once for each telescope. For more information on how the data gathered from this survey will be used or to contact us directly, scroll down to the "Additional Information" and "Contact Information" sections below.
Because an image without mouseover text just feels wrong (a neurosis attributable to repeated conditioning by the likes of one Randall Munroe.)
WHERE do you typically use a telescope?
City/Town, State/Province, Country or Zip Code
What's the nearest city/town to where you observe? (e.g. Venice, Italy or Venice, FL or 90291)
Your answer
What's your approximate latitude in degrees (e.g. +18.443) or degrees/minutes/hemisphere (e.g. 18°27'N)? (If you don't know your latitude, you can try clicking on your observing location in Google Maps to drop a pin, and a popup box should display the LATITUDE, LONGITUDE as a grey hyperlink.)
Your answer
Frequency and Duration
About how many nights per year do you use a telescope?
(or days, for you solar observers)
Your answer
Start time
What time do you typically start observing? Since sunrise and sunset times are so variable, for the sake of argument, assume that it's near one of the equinoxes with sunset at 18:00 (6PM) and sunrise at 06:00 (6AM). (local standard time, not daylight savings time)
End time
What time do you typically stop observing? (local time)
Do you avoid observing when the moon is up?
1 - No (< 10% of the time) ; 2 - Not usually (10%-30% of the time); 3 - Sometimes (30%-70% of the time); 4 - Usually (70-90%); 5 - Yes (> 90% of the time)
2 am?
What percentage of your observing sessions include 2 am?
Your answer
Do you observe year-round or seasonally?
Start date
If seasonally, what is a typical start date (month, day)? (If year-round, leave blank)
End date
If seasonally, what is a typical end date (month, day)? (If year-round, leave blank)
What type of telescope do you typically use?
Check all that apply
Entrance aperture
What size telescope (or binoculars) do you typically use? If more than one, please indicate what percentage of the time you use each.
1% - 20%
21% - 40%
41% - 60%
61% - 80%
2 inches (61 mm) or less
3 inches (62 mm - 86 mm)
4 inches (87 mm - 112 mm)
5 inches (113 mm - 137 mm)
6 inches (138 mm - 163 mm)
7 inches (164 mm - 188 mm)
8 inches (189 mm - 213 mm)
9 or 10 inches (214 mm - 264 mm)
11 or 12 inches (265 mm - 315 mm)
13 or 14 inches (316 mm - 366 mm)
15 or 16 inches (367 mm - 417 mm)
greater than 16 inches (418+ mm)
Focal ratio (i.e. f-number, f-ratio)
Focal ratio = Focal length / Aperture. For example, for an f/4 telescope, enter 4 as your answer.
Your answer
How often do you use the following type of camera? (If never, leave blank.)
1 - almost never (< 10%)
2 - seldom (10%-30%)
3 - some of the time (30%-70%)
4 - most of the time (70-90%)
5 - almost always (> 90%)
Digital Single-Lens Reflex (DSLR)
Charge-Coupled Device (CCD)
Analog (Film)
Visual Observations
How often are you looking through your eyepiece with your naked eye during a typical viewing session? 1 - almost never (< 1%) ; 2 - seldom (1%-2%, about 1 out of every 50-100 minutes); 3 - occasionally (2%-5%, 1 out of every 20-50 minutes); 4 - some of the time (5%-10%, for about 1 out of every 10-20 minutes); 5 - much of the time (10-20%, about 1 out of every 5-10 minutes); 6 - almost constantly (> 20%, more than 1 out of every 5 minutes)
Almost Never (<1%)
Almost Constantly (>20%)
Eyepieces and Magnification
How often do you use an eyepiece with the following magnification? Magnification = Telescope Focal Length / Eyepiece focal length (e.g. 2000 mm / 20 mm = 100). If you use a Barlow lens to increase your magnification, please include the effect of the Barlow lens in calculating your overall magnification factor.
Low power (under 50x)
1 - almost never (< 10%) ; 2 - seldom (10%-30%); 3 - some of the time (30%-70%); 4 - most of the time (70-90%); 5 - almost always (> 90%)
almost never (<10%)
almost always (>90%)
Medium power (50x to 150x)
1 - almost never (< 10%) ; 2 - seldom (10%-30%); 3 - some of the time (30%-70%); 4 - most of the time (70-90%); 5 - almost always (> 90%)
almost never (<10%)
almost always (>90%)
High power (greater than 150x)
1 - almost never (< 10%) ; 2 - seldom (10%-30%); 3 - some of the time (30%-70%); 4 - most of the time (70-90%); 5 - almost always (> 90%)
almost never (<10%)
almost always (>90%)
True Field of View
What's your most common true field of view? (If your value falls between the given options, round to the nearest option.) True Field of View = Eyepiece Apparent Field of View / Magnification (e.g. 50° eyepiece AFOV / 100x Magnification = 0.5° TFOV)
Eyepiece Barrel Diameter
How often do you use the following types of filters? (We'll assume that if you're doing solar observing, you're using a neutral density solar filter, that any spectral filters are in addition to the ND filter)
Moon filter
1 - almost never (< 10%) ; 2 - seldom (10%-30%); 3 - some of the time (30%-70%); 4 - most of the time (70-90%); 5 - almost always (> 90%)
almost never (<10%)
almost always (>90%)
Polarizing filter
1 - almost never (< 10%) ; 2 - seldom (10%-30%); 3 - some of the time (30%-70%); 4 - most of the time (70-90%); 5 - almost always (> 90%)
almost never (<10%)
almost always (>90%)
Color (spectral) filter(s)
Include light pollution reduction (LPR) filters, nebula filters, and other broadband and narrowband filters. Examples include Ultra-high contrast (UHC), Hydrogen-alpha, Hydrogen-beta, and Oxygen-III filters.1 - almost never (< 10%) ; 2 - seldom (10%-30%); 3 - some of the time (30%-70%); 4 - most of the time (70-90%); 5 - almost always (> 90%)
almost never (<10%)
almost always (>90%)
Observing Targets
What type of objects do you typically attempt to observe?
Check all that apply
Tracking capability
Which of the following features does your telescope have? Check all that apply.
Maximum Slew Rate
If you have a motorized mount, what is your telescope's maximum slew rate? Please indicate the units of your answer (e.g. 1400 times the sidereal rate, or 5.8 degrees per second). If you don't have a motorized mount, leave blank.
Your answer
Telescope Mount
Which type of mount do you typically use? Check all that apply.
Zenith viewing limitations
Are there any practical limitations on viewing objects directly overhead with your telescopic setup? Are you more or less likely to view objects at zenith (altitude = 90°) than at other altitudes? Feel free to elaborate in the Comments section below.
Have you ever seen a man-made satellite pass through your telescope's field of view?
Feel free to tell us about it in the Comments section below.
Astronomy Clubs & Organizations
Are you a member of a local astronomy club and/or any astronomy organizations?
Name(s) of Your Club(s) & Organization(s)
If yes, list the astronomy clubs and organizations of which you are a member. (Otherwise, leave blank.)
Your answer
The following parameters may help us extrapolate survey results to regions with few to no respondents.
Who owns the telescope that you typically use?
Level of Formal Education
Select highest level completed
in Earth years
Your answer
Your answer
Type of Astronomer
Here's a place for any additional relevant information you'd be willing to provide about your telescope(s) and observing habits. (e.g. What specific telescope do you have? What are your favorite astronomy apps or websites? Clarify or expound on any of your answers to the questions above.)
Your answer
Suggestions on improving the survey? Let us know!
Your answer
If you're willing, enter your email address below. We'll only use it if we want to follow up with you about your responses and will delete it once we're done analyzing the results of this survey. But feel free to submit your responses without giving us your email address, too.
Your answer
Turing Centrifuge
It's what separates the humans from the spambots
What is the answer to the ultimate question of life, the universe, and everything?
Additional Information
Thank you so much for taking the time to respond to this survey! We're conducting this survey as part of a probabilistic risk assessment of the potential hazards presented to the general public by spaceborne lidar systems. NASA and its partners (including CNES and ESA) use lidar on satellites to make measurements of Earth's surface and atmosphere. Examples include CALIPSO, CATS, ALADIN, and GLAS. Lidar works on the same time-of-flight principle as radar, but using a laser instead of a beam of radio radiation.

The lidar lasers on satellites greatly exceed eye safety standards for observers on the ground for direct, unaided viewing of the laser beam. But, with sufficiently powerful light-collecting optics, it would, in theory, be possible to exceed the retinal damage threshold. So please, NEVER LOOK DIRECTLY INTO A LASER WITH YOUR EYE. We really don’t want to injure anyone! To that end, we're attempting to calculate the odds of one of these lasers causing injury to make sure the risk has been mitigated to an acceptably low level (e.g. lower than the odds of being injured by a piece of orbital debris from the satellite itself when it reenters Earth’s atmosphere someday, which is another risk we must calculate and mitigate to internationally-agreed-upon acceptably low levels).

We’ve so far done our best to model the problem, but many of our input parameters are only educated guesses. For instance, while we can calculate the energy per area that would result from standing in the laser footprint and viewing the beam through a given size and type of telescope, we don’t know how many such telescopes are in use at any given time. Larger telescopes carry a higher risk of injury, but we suspect larger telescopes are less common since they cost more. And if someone is doing all-night observations, we suspect it’s more likely that they’re using a sensor/camera rather than their eye, e.g. for recording star trails or doing long exposures of faint objects.

The particular orbital parameters of our various satellites also affect our modeling. A laser on the ISS has a non-repeating ground track that paints the mid-latitudes but never the polar latitudes and can pass overhead at different times of night. The A-Train constellation of satellites, on the other hand, has a repeating ground track, flies in a solar-synchronous orbit, so it paints all latitudes and always passes overhead at approximately the same time of night. So, the odds of injuring someone depend on things like the percentage of people still out observing at 2 am and whether active astronomers are distributed by latitude in proportion to the overall population.

If you decide this is a phenomenon you want to see for yourself, be sure to make your attempt using a camera rather than your eye; if you are successful, not only will you avoid the risk of retinal damage by using a camera, you'll also have an image to prove you saw the laser flash. A picture is much more convincing than, "Hey guys! I saw a flash of light from space!" And if you're feeling generous, we'd love it if you'd share your images with us. See contact information below. I personally use Heavens Above and search for “CALIPSO” (or “ISS”) in the satellite database to try and find any near-zenith passes over my location.

LINKS TO MORE INFORMATION (and Definition of Acronyms):

Image of lidar pulse captured by Gregg Hendry of Ball Aerospace

CNES: Centre National d'Études Spatiales (the French government space agency)

ESA: European Space Agency

Heavens Above website for finding satellite trajectories:

There are two satellite-borne lidars currently on-orbit: CATS and CALIOP, which are flying on the ISS and CALIPSO respectively. I’ve listed them here, along with other planned future missions (listed as satellite name / lidar instrument’s name, if different) and one past mission:

ISS / CATS (Cloud-Aerosol Transport System)
o 1064 nm, 532 nm, 355 nm
o currently orbiting

CALIPSO / CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization)
o 1064 nm, 532 nm
o downloadable ASCII files of the actual historical ground track:
o currently orbiting

ADM-Aeolus / ALADIN (Atmospheric LAser Doppler INstrument)
o 355 nm
o planned launch in 2017

ICESAT-2 / ATLAS (Advanced Topographic Laser Altimeter System)
o 532 nm
o scheduled for launch in 2018

EarthCARE (Clouds, Aerosols and Radiation Explorer)
o 355 nm
o scheduled for launch in 2018

GEDI (Global Ecosystem Dynamics Investigation)
o 1064 nm
o planned for 2019

MERLIN (Methane Remote Sensing Lidar Mission)
o 1.6 micrometers
o scheduled for the 2021 timeframe

MESCAL (Monitoring the Evolving State of Aerosols and Cloud Layers)
o future mission

ICESat (Ice, Cloud, and land Elevation Satellite) / GLAS (Geoscience Laser Altimeter System)
o 1064 nm and 532 nm
o launched in 2003
o rentered Earth's atmosphere in 2010

Contact Information
Still want to know more? Email us at . We'll do our best to respond to your inquiry!
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