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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"

28088 results found.

  1. Fermi GRB 251118B: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  3. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  4. GRB 251117A: AstroSat CZTI detection
  5. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  6. LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
  7. GRB 251115A: Swift-XRT observations
  8. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  9. GRB 251117A: SVOM/GRM observation of a short burst
  10. LAT GRB251117.51: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  12. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  13. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  14. GRB 251116C: Swift-XRT observations
  15. LIGO/Virgo/KAGRA S251116en: Updated Sky localization
  16. GRB 251116D: Glowbug gamma-ray detection
  17. EP251023a: Assy AZT-20 optical observations
  18. EP251023a: UAFO and AbAO optical observations
  19. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  20. GRB 251116C: SVOM/VT optical upper limit
  21. GRB 251025B: further Mondy optical observations
  22. GRB 251111A: Mondy optical upper limit
  23. GRB 251116B: EP-FXT follow-up observation
  24. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  26. GRB 251116B: LCO optical upper limits
  27. GRB 251116C: LCO optical upper limits
  28. SVOM GRB251116C: Global MASTER-Net observations report
  29. GRB 251116B: SVOM detection of a burst
  30. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  31. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  32. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  33. Fermi GRB 251115A: Global MASTER-Net observations report
  34. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  35. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  36. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  37. GRB 251113A: Glowbug gamma-ray detection
  38. GRB 251112A: Swift-BAT refined analysis
  39. Fermi trigger No 784717756: Global MASTER-Net observations report
  40. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  41. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  42. Fermi GRB 251114A: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  44. Fermi GRB 251113A: Global MASTER-Net observations report
  45. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  46. GRB 251112A: Swift/UVOT Upper Limits
  47. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  48. GRB 251112A: Swift-XRT refined Analysis
  49. GRB 251112B: MAXI/GSC detection
  50. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  51. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  52. GRB 251108B: Glowbug gamma-ray detection
  53. Swift Trigger 1413695: a possible GRB 251112A
  54. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  55. Fermi trigger No 784621743: Global MASTER-Net observations report
  56. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  57. GRB251111A: 1.3m DFOT optical upper limit
  58. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  59. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  60. GRB 251111A: Swift-XRT afterglow detection
  61. GRB 251111A: SVOM/VT optical observations with X-band data
  62. SVOM GRB251111.42: Global MASTER-Net observations report
  63. GRB 251111A: Swift-XRT observations
  64. SVOM GRB251111.22: Global MASTER-Net observations report
  65. GRB 251111A: EP-FXT counterpart detection
  66. GRB 251013C: Chandra X-ray observations and jet break detection
  67. GRB 251111A: SVOM/VT optical observations with VHF data
  68. GRB 251111A: LCO optical observation
  69. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  70. GRB 251103B: Swift-BAT refined analysis
  71. GRB 251106A: Swift/UVOT Upper Limits
  72. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  73. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  74. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  75. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  76. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  77. Fermi trigger No 784329591: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  79. Fermi trigger No 784279167: Global MASTER-Net observations report
  80. SVOM GRB251108.54: Global MASTER-Net observations report
  81. GRB 251102B: SVOM/GRM observation
  82. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  83. SVOM GRB251106.83: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  85. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  86. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  87. GRB 251106A: Swift-XRT afterglow detection
  88. GRB 251106A: Kilonova-Catcher optical upper limit
  89. Fermi GBM Sub-Threshold Detection of GRB 251106A
  90. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  91. GRB 251106A: MASTER optical observations
  92. GRB 251025C: TERI Gamma-ray detection
  93. GRB 251016B: TERI Gamma-ray detection
  94. GRB 251016A: TERI Gamma-ray detection of a short burst
  95. GRB 250920C: TERI Gamma-ray detection
  96. Fermi trigger No 784034269: Global MASTER-Net observations report
  97. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  98. GRB 251105A: Fermi GBM Observation
  99. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  100. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit

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