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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"
  1. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  2. Fermi GRB 240502B: Global MASTER-Net observations report
  3. GRB 240502C: Fermi GBM Final Localization
  4. Fermi GRB 240502A: Global MASTER-Net observations report
  5. GRB 240501B: GRBAlpha detection
  6. GRB 240430A: GRBAlpha detection
  7. GRB 240502B: Fermi GBM Final Real-time Localization
  8. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  9. Integral GRB240502.23: Global MASTER-Net observations report
  10. GRB 240502A long GRB detected by INTEGRAL
  11. GRB 240502A: Fermi GBM Final Real-time Localization
  12. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  13. Fermi GRB 240501A: Global MASTER-Net observations report
  14. Fermi trigger No 736197684: Global MASTER-Net observations report
  15. GRB 240426A: VZLUSAT-2 detection
  16. GRB 240425A: VZLUSAT-2 detection
  17. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  18. GRB240430A: Fermi GBM Final Localization
  19. GRB 240501B: AstroSat CZTI detection
  20. GRB 240501A: Fermi GBM Final Real-time Localization
  21. GRB 240408B: VZLUSAT-2 detection
  22. GRB 240407A: VZLUSAT-2 detection
  23. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  24. X-ray transient EP240414a: Detection of associated supernova
  25. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  26. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  28. Additional DECam GW-MMADS Candidates from three nights of observations
  29. GRB 240425A: GRBAlpha detection
  30. Fermi-LAT gamma-ray observations of IceCube-240424A
  31. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  32. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  33. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  34. GRB 240429A: Fermi GBM Final Real-time Localization
  35. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  36. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  37. LIGO/Virgo/KAGRA S240429an: Retraction of GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S240422ed: ENGRAVE VLT/XShooter spectroscopy of the host galaxy of J-GEM24a
  39. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  40. Fermi GRB 240428A: Global MASTER-Net observations report
  41. GRB 240428A: Fermi GBM Final Real-time Localization
  42. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  43. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  44. EP240426b: AST3-2 optical upper limit
  45. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  46. LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  47. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  48. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  49. EP240426b: EP-WXT detection of a new fast X-ray transient
  50. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  51. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  52. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  53. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  54. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  55. GRB 240426A: AstroSat CZTI detection
  56. EP240426a: YAHPT optical upper limit
  57. XMM-Newton observation of EP240426a
  58. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
  60. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  61. GRB 240414A: NOEMA detection
  62. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  63. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  64. EP240426a: GMG optical upper limit
  65. LVK S240422ed: Further Swift-XRT followup of three sources
  66. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  67. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  69. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  70. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  71. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  72. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  73. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  74. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  75. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  76. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  77. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  78. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  79. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  80. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  81. LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
  82. LIGO/Virgo/KAGRA S240422ed: ANU 2.3m followup of candidate counterparts
  83. LIGO/Virgo/KAGRA S240422ed: Magellan Spectrum of GW-MMADS Candidate AT2024hdo Indicates a Type II SN
  84. GRB 240425A: Fermi GBM Final Real-time Localization
  85. Fermi trigger No 735697285: Global MASTER-Net observations report
  86. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  87. GRB 240419B: Swift-BAT refined analysis
  88. GRB 240421B: Swift-BAT refined analysis
  89. GRB 240422A: Glowbug gamma-ray detection
  90. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  91. LIGO/Virgo/KAGRA S240413p: DESGW DECam Follow-Up
  92. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  93. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  94. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  95. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  96. IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
  97. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  98. LIGO/Virgo/KAGRA S240422ed: MOSFIRE spectroscopy of the DECam GW-MMADS candidate AT 2024hdn
  99. LIGO/Virgo/KAGRA S240422ed: ATCA follow-up of candidate counterparts
  100. LIGO/Virgo/KAGRA S240422ed: MOSFIRE imaging of the DECam GW-MMADS candidate AT 2024hdm

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