This tool provides a convenient interface to display and explore the ZTF Bright Transient Survey sample. It is automatically updated every few hours.
Classification: Drop-down menu to filter using a few general classification categories. The default is "Candidate transients", which excludes events that are judged to be non-transient (including variable stars, stellar flares, and AGNs). Change to "All" to include these (or "Variables" to see only these). The BTS makes no attempt to be complete, at any magnitude, to Galactic events and non-transients: most are removed by the alert filter or by scanners, and will only be saved if it at some point it was considered by someone to possibly be an extragalactic transient.
Custom filter: Require a particular string of characters in the classification. Very limited support for logical operators (& for "and", | for "or") is available. Use the "exclude" box to remove events matching a particular string.
Apply quality cut: Only show objects with light curve coverage both before, around, and after peak, which peaked after 2018 May 1st, which pass the most recent version of the alert filter, whose reference frames are uncontaminated by transient light, which were still visible (elevation > 30 degrees) at night one month after peak, and which were in fields with low Galactic extinction (A_V < 1 mag). This excludes poorly observed events (rising, setting, very bad weather) and produces a higher-quality (but smaller) sample, ensuring that we have good constraints on the time of peak, magnitude of peak, and timescale, aiding with the subsequent rejection of CV's and other false positives. Note that events that are still being observed may change status in and out of the sample as new data points accumulate. In particular, no SN that is still rising will appear in this group since the peak has not yet beek covered. You can customize the quality cut by only requiring specific conditions (be sure uncheck the top-level box if you do this), or invert the filter to show only failed candidates.
Apply purity cut: Only show objects with light curves whose timescale is consistent with the bulk of the SN population or which are close to but not exactly coincident with a galaxy (a PS1 source in the avro data or in the Lasair cross-match list.) This box should generally only be selected if the quality box is also checked, since good light curve coverage is required to make a reliable assessment of the timescale. You can customize the purity cut by requiring a specific condition or requiring both conditions, and you can invert the purity cut to show failed candidates.
Require TESS at peak: Only show objects that were being observed with the TESS-shadowing 1-night cadence program at the time of maximum light.
Require SDSS field: Only show objects in SDSS photometric fields. Setting this flag is advised if reliable host photometry is desired, since PS1 catalog photometry (and host identification) is heavily affected by deblending/shredding.
Show cutouts: Show image cutouts.
P48 - The P48/ZTF discovery image. Dimensions 60"x60".
PS1 - A PS1 RGB stamp covering the same area as the P48 image. Dimensions 60"x60".
host - A PS1 RGB stamp centered on the automatically-matched host, covering a fixed physical size (20 kpc x 20 kpc). Not shown if redshift is unavailable.
crosshairs - Show crosshairs on all image identifying the transient location. If not set, crosshairs appears on mouseover. For host images the transient may be outside the cutout.
Show light curves: Show a small image of the P48 light curve. Red is r-band and green is g-band. Upper limits are not always reliable.
Show columns: Show some additional columns in the table.
Host photometry - Host absolute magnitudes and colors. Use with caution (see below).
Sample flags - Bit codes detailing which cut conditions the transient passed/failed.
Discovery name - The name reported by the first survey to register the transient on TNS.
ZTF name links to: By default clicking the ZTF link goes to the LASAIR page. This can be changed to ALERCE. Note that you have to resubmit the query for this to take effect.
Only show candidates with detections in last X days: Filters the list as described. The light curve database for any individual transient is only updated every 3 days, so the list will be incomplete if this value is set to a number of 3 or less.
Filters: Require a parameter be within the range from Start to End. The parameters are:
| Saved: | Date saved as a candidate by a human scanner. | |
| Peaked: | Date of brightest P48 detection (in any filter). | |
| RA: | Right ascension. | |
| Dec: | Declination. | |
| z: | Redshift. | |
| Rise: | Rise time from half-peak to peak. (This is calculated crudely by linearly interpolating the light curve, including upper limits before the first detection.) | |
| Fade: | Fade time from peak to half-peak. (Calculated the same way as rise time.) | |
| Peak mag: | Peak P48 detected magnitude (will be below actual peak if coverage is poor). This is in whatever filter the brightest magnitude is observed in. | |
| Last mag: | Last detected magnitude. | |
| Abs mag: | Absolute magnitude at (observed) peak, given the observed redshift and extinction. Applies a basic k-correction. | |
| Host abs: | Absolute i-band host magnitude. Incudes a basic color-dependent k-correction. These are unlikely to be reliable for nearby/extended galaxies, especially for PS1 photometry. | |
| Host col: | Host rest-frame g-i color. Not reliable for PS1 (see above, and PS1 photometry is not aperture-matched). | |
| b: | Galactic latitude in degrees. | |
| A_V: | Galactic extinction in V-band in mag. |
Display as: Display a table (with the columns indicated below), or as a 15 x N grid showing only the reference image and/or light curve, or as a CSV file.
Data Columns: Largely the same as the filter information above.
| ZTF ID: | ZTF 9-letter identifier. | |
| TNS ID: | TNS AT/SN code. (A few transients are wrongly matched on TNS.) | |
| Disc ID: | Discovery name posted by the first team to register the transient on TNS. | |
| RA: | Right ascension. | |
| Dec: | Declination. | |
| time: | Time of peak, expressed as JD-2458000. | |
| mag: | Peak P48 measured magnitude. (If the true peak was missed, this is an upper limit.) | |
| M_abs: | Absolute magnitude at measured peak, given the observed redshift and extinction. Applies a basic k-correction. | |
| Rise: | Rise time from half-peak to peak. (This is calculated crudely by linearly interpolating the light curve, including upper limits before the first detection). If no detections or limits deeper than 0.75 mag below peak exist in the post-peak alert history this is given as a limit. | |
| Fade: | Fade time from peak to half-peak. (Calculated the same way as rise time.) If no detections deeper than 0.75 mag below peak exist in the post-peak alert history this is given as a limit. | |
| Duration: | The sum of rise and fade times, i.e. the time above half-maximum. | |
| Type: | Classification from TNS. | |
| Redshift: | Redshift. Often approximate. (For M31/M33 this is D_L*H_0*c.) | |
| Host M_i: | Host absolute magnitude. Incudes a basic color-dependent k-correction. Not reliable for PS1 or nearby galaxies (see above); omitted at z<0.01. | |
| Host g-i: | Host rest-frame g-i color. Not reliable for PS1 or nearby galaxies (see above). | |
| Cuts: | Bit codes indicating which cut criteria the transient passes. | |
| b: | Galactic latitude in degrees. | |
| A_V: | Galactic extinction in V-band in mag. |