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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

2794 results found.

  1. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  2. GRB 241030A: Mondy optical observations
  3. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  4. EP241101a: Possible detection of an optical counterpart with FTW
  5. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  6. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  7. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  8. EP 241026b: LBT possible optical counterpart (brightening source)
  9. GRB 240821A: Keck/LRIS spectroscopic observations
  10. GRB 241026A: SAO RAS observations of possible optical afterglow
  11. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  12. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  13. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  14. EP240918a: Swift-XRT observation
  15. EP240918a: YAHPT Optical Upper Limit
  16. GRB 240912A: Swift-BAT refined analysis
  17. Fast X-ray Transient EP240801a: GMRT radio observations
  18. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  19. GRB 240819A as a likely X-Ray Flash
  20. GRB 240828B : Detection of a possible very soft X-ray transient by SVOM/ECLAIRs
  21. EP240801a: Keck/LRIS spectroscopic redshift confirmation
  22. IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
  23. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  24. EP240801a: NOT optical observations
  25. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  26. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  27. EP240708a: X-ray follow-up observations with Swift/XRT
  28. The EP-WXT source triggered on July 14th is likely a flaring star
  29. GRB 240713A: J-band upper limit from WINTER
  30. GRB240713A: X-ray follow-up observation with EP-FXT
  31. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  32. EP240703a and EP240703b: Swift/XRT upper limits
  33. EP240702a: Swift/XRT upper limit
  34. EP240626a: Montarrenti Observatory optical upper limit
  35. EP240618a: NOT further optical observations
  36. X-ray transient EP240618a: Fermi/GBM non-detection
  37. EP240618a: Swift/XRT upper limit
  38. EP240617a: tentative Swift/XRT detection of the afterglow
  39. GRB 240615A: possible transient detection from Wendelstein observations
  40. EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
  41. Swift Trigger 1235109: a possible GRB 240606A
  42. GRB 240603B: Swift detection of a possible burst
  43. GRB 240529A: MASTER prompt OT detection
  44. The EP-WXT source triggered on June 1st is likely a flaring star
  45. EP240518a: GSP optical upper limit
  46. EP240518a: possibly identified with a flare star by EP-FXT
  47. GRB 240514E: A possible candidate BD-21 1074
  48. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  49. GRB 240514B: GOTO candidate optical counterpart
  50. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  51. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  52. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  53. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  54. GRB 240502C: GOTO possible optical counterpart candidates
  55. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  56. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  57. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  58. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  59. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  60. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  61. EP240426a: YAHPT optical upper limit
  62. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  63. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  64. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  65. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  66. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  67. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  68. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  69. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  70. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  71. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  72. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  73. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  74. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  75. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  76. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  77. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  78. GRB 240419A: Possible ATCA radio detection
  79. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  80. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  81. GRB240418A - Candidate afterglow from NIRES
  82. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  83. IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
  84. EP240417a: YAHPT Optical Upper Limits
  85. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  86. EP240416a: Kinder optical counterpart candidate
  87. GRB 240415A: Mondy optical transient detection
  88. LXT 240402A/GRB 240402B: Swift follow-up observations
  89. EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
  90. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  91. GRB 240414A: Swift detection of a burst
  92. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  93. EP240408a: Swift follow-up observation
  94. X-ray transient EP240331a: Kinder optical upper limits
  95. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  96. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  97. X-ray transient EP240315a: e-MERLIN radio observations
  98. Transient EPW20240219aa: REM optical/NIR further observations
  99. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  100. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection

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