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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').
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"

27117 results found.

  1. EP250828a: Liverpool Telescope upper limits
  2. Swift GRB 250828B: Global MASTER-Net observations report
  3. EP250828a: Global MASTER-Net observations report
  4. EP-WXT trigger 01709200800 : KAIT optical observations
  5. EP250827a: Swift/UVOT Detection
  6. EP250828a: NOT optical counterpart confirmation
  7. EP250828a: SVOM/VT optical candidate
  8. GRB 250828B: Swift detection of a burst
  9. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  10. EP250828a: Optical upper limit with Kinder observations
  11. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  12. EP250827a: LCO observations show fading optical counterpart
  13. GRB 250828A: Fermi GBM Final Localization
  14. EP250828a: Einstein Probe detection of an X-ray transient
  15. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  16. GRID detection of GRB 250824A
  17. Fermi GRB 250827A: Global MASTER-Net observations report
  18. EP250827a: confirmation of optical rebrightening with LCO
  19. EP250827a: GOTO observation of the optical afterglow
  20. GRB 250826A: SVOM/GRM observation
  21. GRB 250827A: Fermi GBM Final Real-time Localization
  22. EP250827A: An optical rebrightening was detected by LCO.
  23. EP250827a: Swift-XRT counterpart detection
  24. The EP-WXT trigger 01709200800 is likely a flaring star
  25. EP250827a: TRT optical observations
  26. EP250827a: BOOTES-7 early optical dectection
  27. EP250827a: Gemini-South redshift z = 1.613
  28. EP250827a: Global MASTER-Net observations report
  29. EP250827a: Gemini-South optical counterpart detection
  30. EP250827a: Einstein Probe detection of an X-ray transient
  31. Fermi GRB 250826A: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  33. Fermi trigger No 777883624: Global MASTER-Net observations report
  34. Fermi Gamma-ray Burst Monitor trigger 777883624/250826283 is not a GRB
  35. GRB 250826A: Fermi GBM Final Real-time Localization
  36. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  37. Fermi GRB 250824B: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  39. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  40. GRB 250823A: Swift-BAT refined analysis
  41. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  42. GRB 250823A: Swift-XRT refined Analysis
  43. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars
  44. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  45. GRB 250824B: Fermi GBM Final Real-time Localization
  46. The EP-WXT trigger 01709200707 is likely a flaring star
  47. GRB 250823A: COLIBRÍ optical observations
  48. The EP-WXT trigger 01709200706 is likely a flaring star
  49. GRB 250823A: SVOM/VT optical observation
  50. GRB 250824A: Fermi GBM Final Real-time Localization
  51. GRB 250823A: Swift/UVOT Detection
  52. GRB 250823A: NOT optical observations
  53. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  54. GRB 250823A: Fermi GBM Observation
  55. GRB 250823A: LCOGT Optical Detection
  56. GRB 250823A: BOOTES6/DPRT early optical detection
  57. GRB 250823A: Liverpool Telescope optical detection
  58. GRB 250823A: Swift detection of a burst
  59. GRB 250823A: Fermi GBM Final Real-time Localization
  60. Swift GRB250823.84: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S250818k: Rebrightening detected with Gemini/GMOS
  62. LIGO/Virgo/KAGRA S250818k: PRIME nIR observations of AT2025ulz
  63. LIGO/Virgo/KAGRA S250818k: JinShan optical observations of AT2025ulz
  64. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  65. LIGO/Virgo/Kagra S250818k: STEP/T80N upper limits on 2025ulz
  66. LIGO/Virgo/KAGRA S250818k: 3 GHz MeerKAT observations of AT2025ulz
  67. IPN triangulation of GRB 250821B (long/bright)
  68. GRB 250821A: Kilonova-Catcher optical upper limits
  69. GRB 250812A: SVOM/ECLAIRs refined analysis
  70. GRB 250821A: Swift-BAT refined analysis
  71. LIGO/Virgo/KAGRA S250818k: NOT optical observations of AT2025ulz
  72. EP250821a: VLT X-shooter spectroscopic redshift z = 0.577
  73. GRB 250821A: VLT/FORS2 Optical Observation
  74. GRB 250821A: GECAM-B detection
  75. GRB 250821B: SVOM/GRM observation
  76. EP250821a: SVOM/VT optical observation
  77. Fermi GRB 250821B: Global MASTER-Net observations report
  78. GRB 250821A: NOT z-band upper limit
  79. GRB 250821C: Fermi GBM Final Real-time Localization
  80. GRB 250821A: Swift-XRT refined Analysis
  81. Swift GRB 250821A: Global MASTER-Net observations report
  82. GRB 250821B: Fermi GBM Detection
  83. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  84. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  85. GRB 250821A: Swift/UVOT Upper Limits
  86. EP250821a: Rapidly fading optical source detected in Las Cumbres followup
  87. EP250821a: Swift XRT and UVOT counterpart detection
  88. LIGO/Virgo/KAGRA S250818k: GOTO counterpart search and upper limits
  89. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  90. GRB 250821A: LCOGT Optical Upper Limits
  91. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  92. LIGO/Virgo/KAGRA S250818k: 10 GHz VLA observations of AT2025ulz
  93. GRB 250821A: Swift detection of a burst
  94. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  95. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  96. EP250821a: Einstein Probe detection of an X-ray transient
  97. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  98. LIGO/Virgo/KAGRA S250818k: Pan-STARRS grizy-band imaging and photometry of AT2025ulz
  99. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  100. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz

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