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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"

22056 results found.

  1. Fermi trigger No 736197684: Global MASTER-Net observations report
  2. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  3. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  4. Additional DECam GW-MMADS Candidates from three nights of observations
  5. Fermi-LAT gamma-ray observations of IceCube-240424A
  6. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  7. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  8. LIGO/Virgo/KAGRA S240422ed: ENGRAVE VLT/XShooter spectroscopy of the host galaxy of J-GEM24a
  9. Fermi GRB 240428A: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  11. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  12. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  13. LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  14. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  15. EP240426b: EP-WXT detection of a new fast X-ray transient
  16. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  17. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  18. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  19. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  20. GRB 240414A: NOEMA detection
  21. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  22. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  23. LVK S240422ed: Further Swift-XRT followup of three sources
  24. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  25. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  26. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  27. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  28. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  29. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  30. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  31. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  32. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  33. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  34. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  35. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  36. LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
  37. LIGO/Virgo/KAGRA S240422ed: ANU 2.3m followup of candidate counterparts
  38. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  39. Fermi trigger No 735697285: Global MASTER-Net observations report
  40. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  41. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  42. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  43. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  44. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  45. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  46. LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
  47. LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm
  48. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  49. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  50. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  51. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  52. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  53. LIGO/Virgo/KAGRA S240422ed: DECam GW-MMADS Candidates
  54. LIGO/Virgo/KAGRA S240422ed: Potential Magellan candidates from GCN 36263 are unrelated.
  55. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  56. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  57. IceCube Alert 240424.08: Global MASTER-Net observations report
  58. LIGO/Virgo/KAGRA S240422ed: Magellan Detection of a Potential Electromagnetic Counterpart
  59. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  60. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  61. LIGO/Virgo/KAGRA S240422ed: LAST optical observations
  62. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  63. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  64. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  65. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  66. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  67. LXT240402A/GRB240402B: Chandra X-ray detection
  68. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  69. GRB 240419A: Possible ATCA radio detection
  70. GRB 240421B: ATCA radio observations
  71. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  72. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  73. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  74. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  75. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  76. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  77. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  78. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  79. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  80. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  81. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  82. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  83. Fermi trigger No 735470374: Global MASTER-Net observations report
  84. GRB 240414A: radio detection with the VLA
  85. Fermi-LAT gamma-ray observations of IceCube-240419A
  86. GRB 240414A: AMI-LA radio observations
  87. GRB 240414A: LBT optical detection
  88. GRB 240415B: Swift-XRT observations
  89. Fermi GRB 240422A: Global MASTER-Net observations report
  90. GRB240421B: Zadko Observations
  91. Fermi GRB 240421B: Global MASTER-Net observations report
  92. Swift GRB 240421B: Global MASTER-Net observations report
  93. GRB 240421B: J-band upper limits from WINTER
  94. GRB 240421B: Swift/UVOT Upper Limits
  95. Fermi GRB 240421A: Global MASTER-Net observations report
  96. EP240420a: TNT upper limit to its optical counterpart
  97. EP240420a: Xinglong decaying optical counterpart
  98. EP240420a: Nanshan optical counterpart observations
  99. EP240420a: NOT optical counterpart candidate and potential host
  100. Fermi trigger No 735280430: Global MASTER-Net observations report

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