Difference: AMPELChannels (1 vs. 16)

• M: Sjoert, T: Sara, W: Suvi, Th: Erica, F: Charlotte

GROWTH Marshal TDE Scanning

• Please see: https://docs.google.com/document/d/1cPJb-u1x9z75NXeUW7hbkagy26ZTd8oNXNvWMGuC4zw/edit

GROWTH Marshal Candidate Scanning Saving Philosophy (no longer used)

• add button that links to the ASASSN light curve tool, https://asas-sn.osu.edu/?days=300&declination=99.9&ra=99.9

Properties (note, this was written prior to the start of ZTF)

Channels designed for discovery of TDEs (note, this was written prior to the start of ZTF)

• Description: Nuclear and Blue flare and large amplitude and near peak

• Description: nuclear and constant color. But no requirement on host color. Less strict requirements on flare color.

• Description: Blue and constant color. Orphan flare or host galaxy mass < 1e10 Msun. Less strict requirement on offset from host (eg, 1").

• Description: Host galaxy mass >1e11 and nuclear flare

• Description: E+A host spectrum or high compactness (cf. the Law-Smith and Graur papers).

• Description: AGN with spectrum and very large amplitude (delta m>1)

• Description: AGN and large flare and BH mass < 1e8 and photometric TDE properties

GROWTH Marshal ZTF Science Validation Filter (not actively used, replaced by Ampel NuclearTransient filter)

• should we add a requirement for 3 consecutive detections, at least one < 20 mag.

• Goal: Early follow-up with moderate contamination, complete for m_g<18.5

• Description: Blue and constant color. Orphan flare or host galaxy mass < 1e10 Msun. Less strict requirement on offset from host (eg, 1").

• Description: Host galaxy mass >1e11 and nuclear flare

• Description: AGN with spectrum and very large amplitude (delta m>1)

• Description: AGN and large flare and BH mass < 1e8 and photometric TDE properties

GROWTH Marshal Nuclear Transients Filter (Version updated on Nov 29, 2018)

def compiledFunction(current_observation):
    filteron = False
    annotations={}
    calccount=10000
    nuclear = False
    large_amp = False
    extended_host = False
    blue_flare = False
    sgscore = 0
    real = False
    mover = True
    brightstar = False
    positiveflux = False
    host_in_ps1 = False
    hasref = False
    near_bright_star = False
    out_of_plane = False
    bright = False
    adjacent_det = False
    crowded = True
    color = 99.0
    prevcandidates = current_observation['prv_candidates']
    b_now = current_observation['candidate']['fid']
    the_other_band = 3 - b_now
    t_now = current_observation['candidate']['jd']
    t_this = (-1)
    offset = current_observation['candidate']['distnr']
    ps1offset = current_observation['candidate']['distpsnr1']
    numofsources = current_observation['candidate']['nmtchps']
    gal_lat = current_observation['candidate']['gal_lat']
    host_mag = current_observation['candidate']['magnr']
    m_now = current_observation['candidate']['magpsf']
    m_this = (-1)
    m_max = m_now
    sgscore = current_observation['candidate']['sgscore1']
    magnr = current_observation['candidate']['magnr']
    distnr = current_observation['candidate']['distnr']
    rbscore = current_observation['candidate']['rb']
    distpsnr1 = current_observation['candidate']['distpsnr1']
    isdiffpos = current_observation['candidate']['isdiffpos']
    srmag = current_observation['candidate']['srmag1']
    if (sgscore < 0.8):
        extended_host = True
        calccount -= 2
    if (math.fabs(gal_lat) > 7):
        out_of_plane = True
        calccount -= 2
    if (numofsources < 40):
        crowded = False
        calccount -= 2
    if (ps1offset < 1.0):
        host_in_ps1 = True
        calccount -= 2
    if (rbscore and rbscore > 0.2):
        real = True
        calccount -= 2
    if (offset < 0.5):
        nuclear = True
        calccount -= 2
    if (magnr and magnr < 15.0 and distnr and distnr < 10):
        brightstar = True
        calccount -= 2
    if (distpsnr1 and distpsnr1 > 2):
        near_bright_star = True
        calccount -= 2
    if (srmag and srmag > 0):
        hasref = True
        calccount -= 2
    if (isdiffpos == 't' or isdiffpos == '1'):
        positiveflux = True
        calccount -= 2
    if (prevcandidates):
        for candidate in (prevcandidates):
            calccount -= 2
            if (candidate['magpsf'] and candidate['jd'] and candidate['fid'] and candidate['isdiffpos'] and (candidate['isdiffpos'] == 't' or candidate['isdiffpos'] == '1')):
                dt = t_now - candidate['jd']
                if (candidate['magpsf'] <= 20):
                    bright = True
                    calccount -= 2
                if (mover == True and dt > 0.02 and candidate['magpsf'] < 99):
                    mover = False
                    calccount -= 2
                if ((color == 99) and (dt < 2.0) and (candidate['fid'] == the_other_band)):
                    if (b_now < the_other_band):
                        color = m_now - candidate['magpsf']
                        calccount -= 2
                    else:
                        color = candidate['magpsf'] - m_now
                        calccount -= 2
                    calccount -= 3
                dt0 = t_this - candidate['jd']
                if (candidate['magpsf'] < 99):
                    if ((adjacent_det == False) and (dt0 > (-1.0))):
                        adjacent_det = True
                        calccount -= 2
                    if (dt0 < 0):
                        t_this = candidate['jd']
                        m_this = candidate['magpsf']
                        calccount -= 3
                    calccount -= 3
                if ((candidate['fid'] == b_now) and (candidate['magpsf'] < m_max)):
                    m_max = candidate['magpsf']
                    calccount -= 2
                calccount -= 8
            if calccount < 0:
                break
        calccount -= 2
    if (adjacent_det == False):
        if ((t_now - t_this) < 1):
            adjacent_det = True
            calccount -= 2
        calccount -= 2
    if (color < 0):
        blue_flare = True
        annotations['blueflare'] = color
        calccount -= 3
    else:
        cont_det = False
        calccount -= 2
    if (m_max and m_max > 0 and host_mag and host_mag > 0):
        delm = (-2.5) * math.log10(10 ** ((-0.4) * host_mag) + 10 ** ((-0.4) * m_max)) - host_mag
        diff_mag = m_max - host_mag
        calccount -= 3
    else:
        delm = (-999)
        diff_mag = (-999)
        calccount -= 3
    annotations['dm'] = delm
    annotations['offset'] = offset
    annotations['color'] = color
    annotations['sgscore'] = sgscore
    annotations['diff_mag'] = diff_mag
    annotations['adjacent_det'] = adjacent_det
    annotations['gal_lat'] = gal_lat
    tde_cand = positiveflux and hasref and real and out_of_plane and nuclear and extended_host and bright and host_in_ps1 and (not brightstar and (not mover and (not near_bright_star and (not crowded))))
    filteron = tde_cand
    return filteron,annotations

GROWTH Marshal Nuclear Transients Filter (Version updated on Jun 29, 2018)

if (numofsources < 40){ crowded = False; }

if (ps1offset < 1.0){ host_in_ps1 = True; }

• should we add a requirement for 3 consecutive detections, at least one < 20 mag.

GROWTH Marshal Scanning Schedule

• M: Sjoert, T: Brad, W: Suvi, Th: Nadia, F: Charlotte, Sat: Sara, Sun: Tiara

GROWTH Marshal Scanning Philosophy

• save any "real" nuclear transient: AGN, TDE, nuclear SN
• remove any variable stars as "stellar"
• don't save faint sources with non detections between detections, but don't remove them as "bogus" until you are sure they are bogus. they will show up again on the scanning page on a later day if they persist and are real.
• remove obvious image artifacts as "bogus" but be careful of bad contrast in the stamp image and lack of an SDSS cut out...you may not be able to see the image properly enough to determine by eye if it is bogus.
• keep an eye out for rb scores and sgscores. note in your scanning report when they appear to be wrong.
• after you save alerts, click on their pages, and make a brief summary of what they are in your scanning report. "blue rising transient", "broad-line QSO", "red, fading transient", etc.
• make sure you are searching 24 hours of alerts, and that you are looking at "nuclear transients" only, and that you select the correct pull-down menu for "nuclear transients" when you "save" and "remove"

GROWTH Marshal Nuclear Transients Filter (Version updated on Apr 25, 2018)

if (srmag and srmag > 0) { hasref = True; }

if (isdiffpos == "t" or isdiffpos == "1") { positiveflux = True; }

if (prevCandidates) {

for candidate in (prevCandidates) {

if (candidate["magpsf"] and candidate["jd"] and candidate["fid"] and candidate["isdiffpos"] and(candidate["isdiffpos"] == "t" or candidate["isdiffpos"] == "1")) {

if ((color = 99) and(dt < 2.0) and(candidate["fid"] = the_other_band)) {

if ((candidate["fid"] == b_now) and(candidate["magpsf"] < m_max)) { m_max = candidate["magpsf"]; }

} } }

if (adjacent_det == False){ if ((t_now - t_this) < 1){ adjacent_det = True;

if (m_max and m_max > 0 and host_mag and host_mag > 0) {

TDE_cand = positiveflux and hasref and real and nuclear and extended_host and not brightStar and not mover and not near_bright_star;

• import SDSS (host) spectrum automatically
• show SDSS (or PS1 if outside footprint) thumb in Program Reports. This makes it easier to identify your fav transient (perhaps safe the thumb image instead of reloading each time).
• add button that links to the ASASSN light curve tool, https://asas-sn.osu.edu/?days=300&declination=99.9&ra=99.9

• add a histogram of distnr values from all the alert packets to the Marshal page.
• manually add new sources to the Marshal, including the light curve, by uploading an .avro package (or via the ZTF name, but .avro uploads should be more easy to implement?).
• automatically push new sources to the Marshal by supplying .avro or .json data (ie, from an Ampel T3 module).
• have a way to link to the scanning page view of the alert packets for a scanned transient.
• be able to add a saved transient to a science program from the Marshal page.
• have information on the number of alerts generated ingested in a night and how many got through your filter.
• indicate (or remove) photometry from Ref-Science (ie, isdiffposs=0); update: looks like this is fixed for more recent alerts.
• option to classify a source without uploading a spectrum (eg, spectroscopic AGN from SDSS). Note, we can also do this by uploading new info in list_program_sources.cgi, which is the preferred method for bulk annotations.

• offset of host galaxy; mean of r and g filter measurement [gets updated as more observations are come in]

• mean g-r color post-peak [gets updated as the source fades]

• color of the host (g-i from PS1; note we only get PSF mags in the alert package)

• stellar mass of the host (from Ampel T2 module)
• variability of the host before the flare (using ZTF PSF data, or perhaps PS1)

• Description: Strict TDE selection; similar to iPTF search.
• Facilities: SEDm
• Code: inside the Marshal, also see code below (might be replaced by Ampel filter once the Marshal accepts auto uploads).

Fainter and near peak

• Steward: Sjoert
• Goal: Remove SNe Ia. Similar to SEDm selection, but to a fainter magnitude limit. Can either trigger u-band or spectroscopy at telescopes bigger than 60-inch.
• Description: Nuclear and Blue flare and large amplitude and near peak
• Facilities: DCT, friends at larger telescopes
• Code: Ampel filter developed in private git repro, contact Sjoert to get access.

• Steward: Sjoert

• Description: nuclear and constant color. But no requirement on host color. Less strict requirements on flare color.
• Facilities: SEDm or spectrograph at larger telescope; Swift.
• Code: Ampel filter. No started yet. Need iPTF data to test how well this idea will work.

• Steward: Sjoert

• Description: Blue and constant color. Orphan flare or host galaxy mass < 1e10 Msun. Less strict requirement on offset from host (eg, 1").
• Facilities: Swift, optical spectroscopy
• Code: not yet, we first need PS1 photoz T2 module

• Steward: Sjoert

• Description: Host galaxy mass >1e11 and nuclear flare
• Facilities: Get optical spectrum
• Code: not yet, we first need PS1 photoz T2 module

• Steward: Sjoert

• Description: E+A host spectrum or high compactness (cf. the Law-Smith and Graur papers).
• Facilities: Optical spectrum; Swift
• Code: not yet, we need some good catalogs

Large AGN flares / Changing look

• Steward: Sara
• Goal: Find extreme AGN
• Description: AGN with spectrum and very large amplitude (delta m>1)
• Facilities: Swift?
• Code: Ampel

TDEs in AGN

• Steward: Sara & Sjoert ?
• Goal: Try to find TDEs in AGN
• Description: AGN and large flare and BH mass < 1e8 and photometric TDE properties
• Facilities: depends on how bright the AGN is
• Code: not yet, first need to make AGN flares

• Facilities: HST proposal (PI: Cenko)

• Goal: Trigger XMM

• Facilities: HST proposal (PI: Gezari)

• Facilities: VLA proposal (PI: van Velzen)

• indicate (or remove) photometry from Ref-Science (ie, isdiffposs=0)

• manually add new sources to the Marshal, including the light curve, by uploading an .avro package (or via the ZTF name, but .avro uploads should be more easy to implement?)
• automatically push new sources with annotations to the Marshal (ie, from an Ampel T3 module)

GROWTH Marshal wish list

• add a histogram of distnr values from all the alert packets to the Marshal page
• have a way to link to the scanning page view of the alert packets for a scanned transient
• be able to add a saved transient to a science program from the Marshal page
• have information on the number of alerts generated ingested in a night and how many got through your filter

GROWTH Marshal Nuclear Transients Filter (version through Feb 28, 2018)

GROWTH Marshal ZTF Science Validation Filter

prevCandidates = observation["prv_candidates"]; m_now = observation["candidate"]["magpsf"]; t_now = observation["candidate"]["jd"]; fid_now = observation["candidate"]["fid"]; sgscore = observation["candidate"]["sgscore"]; rbscore = observation["candidate"]["rb"]; magnr = observation["candidate"]["magnr"]; distnr = observation["candidate"]["distnr"];

bright = m_now < 99.0;

if (observation["candidate"]["isdiffpos"] and (observation["candidate"]["isdiffpos"] = "t" or observation["candidate"]["isdiffpos"] = "1")){ positiveSubtraction = True; } if (rbscore and rbscore > 0.2) { real = True; }

if (sgscore and sgscore > 0.6) { noPointUnderneath = False; }

if (magnr and magnr < 15.0 and distnr and distnr < 10) { brightStar = True; }

for candidate in prevCandidates{ if (candidate["jd"] and candidate["magpsf"] and candidate["fid"] and candidate["isdiffpos"] and (candidate["isdiffpos"] = "t" or candidate["isdiffpos"] = "1")) {

dt = t_now - candidate["jd"]; if (dt > 0.02 and candidate["magpsf"] < 99) { mover = False; }

if (dt = 0.0 and candidate["magpsf"] < 99){ if (candidate["jd"] > t_slope and candidate["fid"] == fid_now) { t_slope = candidate["jd"]; slope = (m_now - candidate["magpsf"]) / dt; } } } }

annotate "magnitude" m_now; annotate "sgscore" sgscore; annotate "slope" slope; annotate "rbscore" rbscore; annotate "mover" mover; annotate "real" real; annotate "positiveSubtraction" positiveSubtraction; annotate "brightStar" brightStar; annotate "magnr" magnr; annotate "distnr" distnr;

filteron bright and noPointUnderneath and not mover and real and positiveSubtraction and not brightStar;

GROWTH Marshal Nuclear Transients Filter

nuclear = False;
large_amp = False;
extended_host = False;
blue_flare = False;
sgscore = 0;

color = 99.0;
prevCandidates = observation["prv_candidates"];
b_now = observation["candidate"]["fid"];
the_other_band = 3 - b_now;
t_now = observation["candidate"]["jd"];
offset = observation["candidate"]["distnr"];
host_mag = observation["candidate"]["magnr"];
m_now = observation["candidate"]["magpsf"];
m_max = m_now;
sgscore = observation["candidate"]["sgscore"];
magnr = observation["candidate"]["magnr"];
distnr = observation["candidate"]["distnr"];


if (observation["candidate"]["sgscore"] < 0.3){
    extended_host = True;
}


if (offset < 0.8){
    nuclear = True;
}

if (magnr and magnr < 15.0 and distnr and distnr < 10) {
   brightStar = True; 
} 

for candidate in prevCandidates{
    dt = t_now - candidate["jd"];
    if (dt != 0.0){
        if ((candidate["fid"] == b_now) and (candidate["magpsf"] < m_max)) {
        m_max = candidate["magpsf"];
    }
    if ((dt < 2.0) and (candidate["fid"] == the_other_band)){
        if (b_now < the_other_band){
        color = m_now - candidate["magpsf"]; 
    }
    else {
        color = candidate["magpsf"] - m_now;
    }
}
}
}

if (color < 0){
    blue_flare = True;
    annotate "blueflare" color; 
}

delm = -2.5*log10(10**(-0.4*host_mag) + 10**(-0.4*m_max)) - host_mag;
if (delm < -0.3){
    large_amp = True;
}

annotate "dm" delm;
annotate "offset" offset;
annotate "color" color;
annotate "sgscore" sgscore;

Properties

Below a list of properties that can be used for TDE identification. Feel free to add more items to the list.

Two urgent questions: can all of these be computed by AMPEL if we provide the code and catalogs? If not, how do we best feed this into the Marshal?

Flare photometric properties:

• offset of host galaxy; mean of r and g filter measurement, including an uncertainty [this property should be updated as more ZTF observations of the flare are obtained]
• g-r color of transient at peak
• mean g-r color post-peak [to be updated as the source fades]
• amplitude of the flare compared to host baseline level (either from PS1 or ZTF magnitude in reference image)

Host only:

• color of the host (g-i from PS1)
• match to one of our AGN catalogs
• compactness/size of the host (from PS1)
• stellar mass of the host
• variability of the host before the flare (using ZTF data, or perhaps PS1)
• no host / orphan source

Channels designed for discovery of TDEs

To be able to conduct a systematic search, it is important that we try to keep many of these channels unchanged (although there will likely be a phase of improvements and updates during the first months of the survey).

• Steward: Tiara
• Goal: Early follow-up with moderate contamination, complete for m_g<18.5
• Description: Strict TDE selection; similar to iPTF search. Red host, blue flare near peak, large amplitude, not AGN. * Facilities: SEDm
• Code: [url?]

U-band selection follow-up

• Steward:
• Goal: Remove SNe Ia. Similar to SEDm selection, but to a fainter magnitude limit.
• Description: Blue flare near peak, large amplitude. * Facilities: DCT, plus others??
• Code: [url?]

Late identifications

• Steward:
• Goal: Completeness! Make sure we get a spectrum if the flare didn't pass the strict cuts near peak, but turns out to be a good candidate when more data comes in.
• Description: Requirement: nuclear, constant color. No requirement on host color.
• Facilities: SEDm or spectrograph at larger telescope; Swift.
• Code:

Low mass host galaxy or orphan TDEs

• Steward: Sjoert + ?
• Goal: Make sure TDEs in low mass galaxies are not missed (eg, because galaxy center is harder to measure).
• Description: Orphan flare or host galaxy mass < 1e10 Msun. Blue flare with constant color. Less strict requirement on offset from host (eg, 1").
• Facilities: Get optical spectrum, trigger Swift if TDE.
• Code:

High mass host galaxy

• Steward: Sjoert + ?
• Goal: Find more sources like ASASSN-15lh
• Description: Host galaxy mass >1e11, nuclear flare.
• Facilities: Get optical spectrum

Post-starburst host galaxy

• Steward ?
• Goal: Completeness for flares from host galaxies that are known to overproduce TDEs.
• Description: E+A spectrum of host OR high compactness (cf. the Law-Smith and Graur papers).
• Facilities: Optical spectrum; Swift
• Code:

Large AGN flares

• Steward ?
• Goal: Get some handle on TDEs in AGN or find extreme AGN.
• Description: AGN and very large amplitude (delta m>1), BH mass < 1e9
• Facilities: Optical spectrum, Swift XRT?
• Code:

High-level Channels for confirmed TDEs

HST

• Steward: Brad
• Goal: Get UV spectra
• Description: TDE identification based on optical spectrum (any other requirements? like detection in NUV by Swift?) * Facilities: HST proposal (PI: Cenko)

XMM

• Steward: Suvi
• Goal: Get UV spectra
• Description: TDE identification based on optical spectrum (any other requirements? like XRT detection?) * Facilities: HST proposal (PI: Gezari)

VLA

• Steward: Sjoert
• Goal: Get radio follow-up
• Description: TDE identification based on optical spectrum; within few weeks from peak * Facilities: VLA proposal (PI: van Velzen)

SEDm TDEs

• Steward: Tiara Hung
• Description:
• Code:

-- SuviGezari - 17 Jan 2018