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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').
Advanced Search

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"

24638 results found.

  1. Swift GRB241127.91: Global MASTER-Net OT detection
  2. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  3. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  4. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  5. EP241126a: Optical Upper limits with Kinder observations
  6. IPN triangulation of GRB 241114B
  7. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  8. EP241126a: GSP detects optical counterpart
  9. EP241126a: TRT optical counterpart detection
  10. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  11. EP241126a: EP detection of a fast X-ray transient
  12. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  13. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  14. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  15. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  16. GECAM detection of a short burst from SGR 1830
  17. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  18. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  19. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  20. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  21. GRB 241026A: radio detection with the VLA
  22. EP241125a: Optical upper limit with Kinder observations
  23. EP241125a: EP detection of an X-ray transient
  24. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  25. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  26. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  27. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  28. LIGO/Virgo/KAGRA S241125n: Updated Sky localization
  29. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  30. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  31. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  32. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  33. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  34. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  35. LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
  36. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  37. IPN triangulation of GRB 241117A
  38. GRB 241026A: VIRT Optical Upper Limit
  39. GRB 241025A: VIRT Optical Upper Limit
  40. GRB241120A: OHP/T193 optical observations
  41. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  42. GRB 241120A: Mondy and AbAO optical observations
  43. EP241119a: Optical upper limits with Kinder observations
  44. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  45. EP241119a: GIT optical upper limits
  46. EP241119a : J-band observations with WINTER
  47. GRB 241120A: Fermi GBM Observation
  48. EP241119a: EP detection of a fast X-ray transient
  49. GRB241120A: a long GRB detected by INTEGRAL
  50. GRB 241112B: Mephisto further optical observations
  51. GRB 241030A: J-band observations
  52. GRB 241115a: PRIME near-infrared upper limits
  53. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  54. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  55. GRB 241115B: Fermi GBM Observation
  56. LIGO/Virgo/KAGRA S241114y: Updated Sky localization
  57. Updates to IceCube realtime alert system for muon tracks
  58. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  59. GRB 241117A: Fermi GBM Detection
  60. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  61. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  62. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  63. GRB 241115C: Fermi GBM Observation
  64. GRB 241115A: Swift-XRT afterglow detection
  65. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  66. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  67. GRB 241115A: Mephisto upper limits
  68. GRB 241113B: Mephisto upper limits
  69. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  70. GRB 241115D / EP 241115a: SVOM/GRM observation
  71. EP241113a: Swift XRT weak detection
  72. GRB 241115A: Fermi GBM Observation
  73. GRB 241115A: LCOGT Optical Upper Limits
  74. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  75. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  76. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  77. EP241115a: EP detection of a fast X-ray transient
  78. Swift GRB 241115A: Global MASTER-Net observations report
  79. Fermi GRB 241115A: Global MASTER-Net observations report
  80. GRB 241115A: Swift detection of a burst
  81. EP 241113a: LBT possible optical counterpart
  82. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  83. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  84. GRB 241113A: Swift-BAT refined analysis
  85. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  86. GRB 241113A: PRIME near-infrared upper limits
  87. EP241113a: Global MASTER-Net observations report
  88. GRB 241113B: J-band upper limit from WINTER
  89. GRB 241113A: J-band observations with WINTER
  90. EP241113a : J-band observations with WINTER
  91. GRB 241030A: LCO optical observation
  92. GRB 241113B: Swift-XRT observations
  93. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  95. EP241113b/GRB 241113B: EP detection of GRB 241113B
  96. Fermi-LAT gamma-ray observations of IceCube-241113A
  97. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  98. GRB 241113A: Swift-XRT refined Analysis
  99. GRB 241113A: Swift/UVOT Detection
  100. GRB 241113A: REM detection of the optical/NIR afterglow

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