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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"

32508 results found.

  1. Fermi GRB 240511A: Global MASTER-Net observations report
  2. Swift GRB 240511A: Global MASTER-Net observations report
  3. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  4. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  6. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  7. EP240506a: Xinglong optical upper limit
  8. EP240506a: CrAO ZTSH optical upper limit
  9. GRB 240504A: Fermi GBM Observation
  10. EP240506a: Archival radio searching
  11. EP240506a: TRT optical upper limit
  12. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  13. EP240506a: Optical upper limit with Kinder observations
  14. IPN triangulation of GRB 240504A
  15. GRB 240502A: 1.3m DFOT Optical upper limit
  16. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  18. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  19. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  20. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  21. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  22. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  23. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  24. Fermi GRB 240504A: Global MASTER-Net observations report
  25. LXT 240402A / GRB 240402B: VLT X-shooter redshift of host
  26. GRB 240502A: GOTO optical upper limit
  27. GRB 240502A: Fermi GBM Observation
  28. GRB 240415A 1.3m DFOT Optical upper limit
  29. GRB 240502C: GOTO possible optical counterpart candidates
  30. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  31. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  32. Fermi GRB 240502B: Global MASTER-Net observations report
  33. Fermi GRB 240502A: Global MASTER-Net observations report
  34. GRB 240501B: GRBAlpha detection
  35. GRB 240430A: GRBAlpha detection
  36. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  37. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  38. Fermi GRB 240501A: Global MASTER-Net observations report
  39. GRB 240426A: VZLUSAT-2 detection
  40. GRB 240425A: VZLUSAT-2 detection
  41. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  42. GRB 240408B: VZLUSAT-2 detection
  43. GRB 240407A: VZLUSAT-2 detection
  44. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  45. X-ray transient EP240414a: Detection of associated supernova
  46. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  47. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  49. Additional DECam GW-MMADS Candidates from three nights of observations
  50. GRB 240425A: GRBAlpha detection
  51. Fermi-LAT gamma-ray observations of IceCube-240424A
  52. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  53. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  54. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  55. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  56. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  57. LIGO/Virgo/KAGRA S240422ed: ENGRAVE VLT/XShooter spectroscopy of the host galaxy of J-GEM24a
  58. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  59. Fermi GRB 240428A: Global MASTER-Net observations report
  60. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  61. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  62. EP240426b: AST3-2 optical upper limit
  63. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  64. LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  65. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  66. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  67. EP240426b: EP-WXT detection of a new fast X-ray transient
  68. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  69. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  70. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  71. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  72. EP240426a: YAHPT optical upper limit
  73. XMM-Newton observation of EP240426a
  74. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  76. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  77. GRB 240414A: NOEMA detection
  78. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  79. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  80. EP240426a: GMG optical upper limit
  81. LVK S240422ed: Further Swift-XRT followup of three sources
  82. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  83. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  85. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  86. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  87. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  88. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  89. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  90. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  91. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  92. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  93. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  94. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  95. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  96. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  97. LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
  98. LIGO/Virgo/KAGRA S240422ed: ANU 2.3m followup of candidate counterparts
  99. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  100. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates

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